Strategic bombing is a military strategy used in a total war with the goal of defeating an enemy nation-state by destroying its economic ability and public will to wage war rather than destroying its land or naval forces. It is a systematically organized and executed attack from the air which can utilize strategic bombers, long- or medium-range missiles, or nuclear-armed fighter-bomber aircraft to attack targets deemed vital to an enemy's war-making capacity.
One of the aims of war is to demoralise the enemy, so that peace or surrender becomes preferable to continuing the conflict. Strategic bombing has been used to this end. The phrase "terror bombing" entered the English lexicon towards the end of World War II and many strategic bombing campaigns and individual raids have been described as terror bombing by commentators and historians although, because the term has pejorative connotations, others have preferred to use other terms such as "will to resist (by which I mean morale)".
The use of air power and strategic bombing was advocated by Giulio Douhet, and was publicised by Stanley Baldwin's 1932 comment the bomber will always get through. Douhet's theories were advocated in America by Billy Mitchell.
While the distinction between tactical, operational, and strategic bombing can be blurred, they are distinct methodologies generally used for different purposes. Strategic bombing is a methodology distinct from both tactical bombing and the use of strategic air assets in an operational capacity.
Such a strategy usually involves sustained attacks over a period of time on targets that affect a nation's overall war making capability, such as factories, railroads, oil refineries, and other resources. Less frequently, individual strategic attacks are made against 'point' targets, such as Britain's RAF Bomber Command attacks against the Ruhr dams by means of the bouncing bomb designed by Barnes Wallis in May 1943.
As strategic bombing aims to undermine an enemy nation-state's ability to wage war, strategic bombers need to be able to reach targets throughout most or all of that nation, and so have tended to be larger, longer-ranged aircraft. Strategic bombers have also been used to support major military ground operations, such as the isolation of Normandy through the bombing of transportation hubs throughout northern France in support of the D-Day invasion, or the carpet bombing of the Axis front lines west of Saint-Lô in support of Operation Cobra.
An aerial attack strategy of deliberately bombing and/or strafing civilian targets in order to break the morale of an enemy, make its civilian population panic, bend the enemy's political leadership to the attacker's will, or to "punish" an enemy, while strategic in nature, is more correctly termed terror bombing.
There are three basic methods used to deliver ordnance onto targets in a strategic bombing campaign. The first is by gravity-dropping large numbers of iron bombs or "dumb bombs", using strategic bombers. The second is through the use of more precise ordnance, precision-guided munitions (so-called smart bombs); cruise missiles fall into this category, though they are not always air-launched. The third method involves the use of nuclear ordnance, either onto a battlefield in a method similar to carpet bombing, or onto a strategic target, as with iron bombs in WW II.
Although the deployment of nuclear weapons from aircraft falls into the category of strategic bombing, and likely represents the ultimate form of both strategic and terror bombing, the term strategic bombing is generally used in reference to the release of non-nuclear air-ground ordnance from strategic aircraft.
Area attack by multiple bombers is based upon detailed calculations of the intended Damage Expectancy or "DE" directed by the Air Tasking Order (ATO) used in a military strategy. To achieve a particular DE, planners select a bomb type based on that particular weapon's damage mechanism - blast/fragmentation or incendiary, for example. Planners then calculate the Single Sortie Probability of Damage (SSPD) and extrapolate from there, adding sorties until the probability of damage meets or exceeds the required DE.
As weapons have grown more precise, the need for mass formations dropping masses of bombs has decreased, and it is now possible for a single bomb to accomplish what in the past took many bombers. In fact, one B-52 can now drop a single bomb from many miles away that can be programmed to strike a target as small as a window or doorway from a chosen direction and at a preselected angle. This can focus the blast in a given direction and can dramatically reduce the risk of collateral damage to other buildings and consequent unintended civilian casualties.
Strategic bombing by multiple modern strategic bombers like the B-52 can be likened to an hour during the Somme bottled into a thirty-second time period. However, some believe this delivery method has been rather ineffective in attacking a nation's warmaking capability, due to the imprecise nature of the attack. Others cite the destruction of enemy infrastructure, resources expended on civil defense and physical protection of sites, and the reallocation of military resources away from the battlefield in order to staff response and air and ground antiaircraft assets as proof of its efficacy. In either case, the unintended mass civilian casualties, terror caused, and ethical questions raised draws adverse long-term attention to the morality of strategic bombing.
Carpet bombing, often confused with strategic bombing, is the use of strategic air assets for operational objectives in support of ground forces. Its use during Operation Cobra is the best-known example. Carpet bombing is viewed ambivalently by ground forces, due to the nigh-inevitable friendly casualties caused by bombers dropping their ordnance short of the aiming point, either through error or "bomb creep".
The use of "smart" weapons is preferred by some nations for two reasons. First, it can be less devastating. Due to the greater accuracy (the smaller CEP) of precision guided weapons, there is less risk of civilian casualties. The second reason is the more-focused damage associated with precision weapons. Strategic bombing can destroy an entire block, but miss the vital components of a factory. Precision weapons can attack precise components of designated targets, increasing the likelihood of a successful attack. However, the 'shock' value of precision bombing is less severe than of area bombing. Unless multiple precision weapons are used, an enemy may seek cover or disperse to different parts of the targeted area. Additionally, area bombing can have an initial significant psychological effect, as the bombing of cities early in World War II terrified their citizens.
One of the aims of war is to demoralise the enemy; facing continual death and destruction may make the prospect of peace or surrender preferable. The proponents of strategic bombing between the world wars, such as General Douhet, expected that direct attacks upon a country's cities by strategic bombers would lead to rapid collapse of civilian morale, so that political pressure to sue for peace would lead to a rapid conclusion. When such attacks were tried in the 1930s—in the Spanish Civil War and the Second Sino-Japanese War—they were ineffective. Commentators observed the failures and some air forces, such as the Luftwaffe, concentrated their efforts upon direct support of the troops.
"Terror bombing" is an emotive term used to describe aerial attacks planned to weaken or break enemy morale. Use of the term to describe aerial attacks implies the attacks are criminal according to the law of war, or if within the laws of war are nevertheless a moral crime. According to John Algeo in Fifty years among the new words the first recorded usage of "Terror bombing" in a United States publication was in a Readers Digest article dated June 1941, a finding confirmed by the Oxford English Dictionary. 
Aerial attacks described as terror bombing are often long range strategic bombing raids, although attacks which result in the deaths of civilians may also be described as such, or if the attacks involve fighters strafing they may be labelled "terror attacks."
German propaganda minister Joseph Goebbels and other high ranking officials of the Third Reich frequently described attacks made on Germany by the Royal Air Force (RAF) and the United States Army Air Force (USAAF) during their strategic bombing campaigns as terrorangriffe - terror attacks.  The Allied governments usually described their bombing of cities with other euphemisms such as area bombing (RAF) or precision bombing (USAAF), and for most of World War II the Allied news media did the same. However, at a SHAEF press conference on 16 February 1945, two days after the Bombing of Dresden, British Air Commodore Colin McKay Grierson replied to a question by one of the journalists that the primary target of the bombing had been on communications to prevent the Germans from moving military supplies and to stop movement in all directions if possible. He then added in an offhand remark that the raid also helped destroy "what is left of German morale." Howard Cowan, an Associated Press war correspondent, filed a story about the Dresden raid. The military press censor at SHAEF made a mistake and allowed the Cowan cable to go out starting with "Allied air bosses have made the long awaited decision to adopt deliberate terror bombing of great German population centres as a ruthless expedient to hasten Hitler's doom." There were followup newspaper editorials on the issue and a longtime opponent of strategic bombing, Richard Stokes, MP, asked questions in the House of Commons on 6 March.
The controversy stirred up by the Cowan news report reached the highest levels of the British Government when on 28 March 1945 the Prime Minister, Winston Churchill, sent a memo by telegram to General Ismay for the British Chiefs of Staff and the Chief of the Air Staff in which he started with the sentence "It seems to me that the moment has come when the question of bombing of German cities simply for the sake of increasing the terror, though under other pretexts, should be reviewed...." Under pressure from the Chiefs of Staff and in response to the views expressed by Chief of the Air Staff Sir Charles Portal, and the head of Bomber Command, Arthur "Bomber" Harris, among others, Churchill withdrew his memo and issued a new one. This was completed on 1 April 1945 and started instead with the usual British euphemism for attacks on cities: "It seems to me that the moment has come when the question of the so called 'area-bombing' of German cities should be reviewed from the point of view of our own interests....".
Many strategic bombing campaigns and individual raids of aerial warfare have been described as "terror bombing" by commentators and historians since the end of World War II, but because the term has pejorative connotations, others have denied that such bombing campaigns and raids are examples of "terror bombing".
See main article: Strategic bombing during World War I. Strategic bombing was used in World War I, though it was not understood in its present form. The first strategic bombing mission of the war was probably the dropping of eight bombs from a German airship over Antwerp on the night of 24-25 August 1914. Within a year or so, specialized aircraft and dedicated bomber squadrons were in service on both sides. These were generally used for tactical bombing; the aim was that of directly harming enemy troops, strongpoints, or equipment, usually within a relatively small distance of the front line. Eventually, attention turned to the possibility of causing indirect harm to the enemy by systematically attacking vital rear-area resources.
The first-ever dirigible aerial bombardment of civilians was on January 19, 1915, when two German Zeppelins dropped 24 fifty-kilogram (110 pound) high-explosive bombs and ineffective three-kilogram incendiaries on the Eastern England towns of Great Yarmouth, Sheringham, King's Lynn, and the surrounding villages. In all, four people were killed and sixteen injured, and monetary damage was estimated at £7,740 (about US$36,000 at the time). German dirigibles also bombed Liepāja in Latvia on the Eastern Front in January 1915.
In 1915 there were 19 more raids, in which 37 tons of bombs were dropped, killing 181 people and injuring 455. Raids continued in 1916. London was accidentally bombed in May, and in July the Kaiser allowed directed raids against urban centers. There were 23 airship raids in 1916, in which 125 tons of ordnance were dropped, killing 293 people and injuring 691. Gradually British air defenses improved. In 1917 and 1918, there were only 11 Zeppelin raids against England, and the final raid occurred on August 5, 1918, which resulted in the death of KK Peter Strasser, commander of the German Naval Airship Department.
By the end of the war, 51 raids had been undertaken, in which 5,806 bombs were dropped, killing 557 people and injuring 1,358. The Zeppelin raids were complemented by the Gotha bomber, which was the first heavier-than-air bomber to be used for strategic bombing. It has been argued that the raids were effective far beyond the material damage caused, in diverting and hampering wartime production and in diverting twelve squadrons and over 10,000 men to air defenses.
The French army on June 15, 1915, attacked the German town of Karlsruhe, killing 29 civilians and wounding 58. Further raids followed until the Armistice in 1918. In a raid in the afternoon of June 22, 1916, the pilots used outdated maps and bombed the location of the abandoned railway station, where a circus tent was placed, killing 120 persons, most of them children.
In contrast, the British launched their own form of strategic bombing. At the start of the war, there were attacks by bombers of the Royal Navy Air Service (RNAS) against the Zeppelin production lines and their sheds at Cologne and Düsseldorf on September 22 and October 8, 1914. In late 1915, the order was given for attacks on German industrial targets and the 41st Wing was formed from units of the RNAS and Royal Flying Corps. The RNAS took to strategic bombing in a bigger way than the RFC, who were focussed on supporting the infantry actions of the Western Front. At first the RNAS attacked the German submarines in their moorings and then steelworks further in targeting the origin of the submarines themselves.
In early 1918 they operated their "round the clock" bombing raid, with lighter bombs attacking the town of Trier by day and large HP O/400s attacking by night. In April 1918, the Independent Force, an expanded bombing group, was created and by the end of the war had aircraft that could reach Berlin but were never used.
Following the war, the concept of strategic bombing developed. The calculations which were performed on the number of dead to the weight of bombs dropped would have a profound effect on the attitudes of the British authorities and population in the interwar years because as bombers became larger it was fully expected that deaths from aerial bombardment would approach those anticipated in the Cold War from the use of nuclear weapons. The fear of aerial attack on such a scale was one of the fundamental driving forces of British appeasement in the 1930s.
The first instances of aerial bombing of cities occurred during the First World War with bombing attacks by Zeppelins over England. They were ineffective, but generated a wave of hysteria, partially attributed to media. This revealed the tactic's potential as a weapon that was of use for propagandists on both sides. Attacks continued and were also joined by heavier-than-air warplanes. These were relatively minor raids by later standards but had the effect of diverting resources of guns and aircraft to the defense of Great Britain.
During the interwar period (1919–1939) the use of aerial bombing was developed as part of British colonial policy, with Hugh Trenchard as its leading proponent. In Iraq, about 1924, the techniques of so-called "Air Control" were developed – which included target marking and locating, as well as formation flying, by the "Trenchard school" which included Sir Charles Portal, Sir Arthur Harris, and Sidney Bufton.
These early developments of aerial warfare led to two distinct branches in the writings of air warfare theorists: tactical air warfare and strategic air warfare. Tactical air warfare was developed as part of a combined-arms attack which would be developed to a significant degree by Germany, and which contributed much to the success of the Wehrmacht during the first four years (1939–42) of World War II. The German Luftwaffe became a major element of the German blitzkrieg.
Three of the leading theorists of strategic air warfare, namely strategic bombing during this period were the Italian Giulio Douhet, the Trenchard school in Great Britain, and General Billy Mitchell in the United States. These theorists thought that aerial bombardment of an enemy's homeland would be an important part of future wars. Not only would such attacks weaken the enemy by destroying important military infrastructure, they would also break the morale of the civilian population, forcing their government to capitulate. Although area bombing theorists acknowledged that measures could be taken to defend against bombers – using fighter planes and antiaircraft artillery - the maxim of the times remained "the bomber will always get through". These theorists for strategic bombing argued that it would be necessary to develop a fleet of strategic bombers during peacetime, both to deter any potential enemy, and also in the case of a war, to be able to deliver devastating attacks on the enemy industries and cities while suffering from relatively few friendly casualties before victory was achieved.
During the Spanish Civil War, the bombing of Guernica by German aviators including the Condor Legion, under Franco-Spanish command, resulted in the near destruction of that Spanish town, and casualties estimated to be between 500 and 1500 people. Though this figure was relatively small, aerial bombers and their weaponry were continually improving – already suggesting the devastation what was to come in the near future.
The practice of area bombardment came to prominence during World War II with the use of large numbers of unguided gravity bombs, often with a high proportion of incendiary bombs, to effect indiscriminate bombing of the target region – either to destroy personnel and/or materiel, or as a means to demoralize the enemy. The high explosive bombs were often on timers and used to intimidate or kill firemen putting out the fires caused by the incendiaries. This, in high enough concentration was capable of producing a firestorm effect.
Initially, this was effected by multiple aircraft, often returning to the target in waves. Nowadays, a large bomber or missile can be used to create the same effect on a small area (an airfield, for example) by releasing a relatively large number of smaller bombs.
In the period between the two world wars, military thinkers from several nations advocated strategic bombing as the logical and obvious way to employ aircraft. Domestic political considerations saw to it that the British worked harder on the concept than most. The British Royal Flying Corps and Royal Naval Air Service of the Great War had been merged in 1918 to create a separate air force, which spent much of the following two decades fighting for survival in an environment of severe government spending constraints.
Royal Air Force leaders, in particular Air Chief Marshal Hugh Trenchard, believed the key to retaining their independence from the senior services was to lay stress on what they saw as the unique ability of a modern air force to win wars by unaided strategic bombing. As the speed and altitude of bombers increased in proportion to fighter aircraft, the prevailing strategic understanding became "the bomber will always get through". Although anti-aircraft guns and fighter aircraft had proved effective in the Great War, it was accepted there was little warring nations could do to prevent massive civilian casualties from strategic bombing. High civilian morale and retaliation in kind were seen as the only answers. (A later generation would revisit this, as Mutual Assured Destruction.)
In Europe, the air power prophet General Giulio Douhet asserted the basic principle of strategic bombing was the offensive, and there was no defence against carpet bombing and poison gas attacks. Douhet's apocalyptic predictions found fertile soil in France, Germany, and the United States, where excerpts from his book The Command of the Air (1921) were published. These visions of cities laid waste by bombing also gripped the popular imagination and found expression in novels such as Douhet's The War of 19-- (1930) and H.G. Wells's The Shape of Things to Come (1933) (filmed by Alexander Korda as Things to Come (1936)).
Douhet's proposals were hugely influential amongst airforce enthusiasts, arguing as they did that the bombing air arm was the most important, powerful and invulnerable part of any military. He envisaged future wars as lasting a matter of a few weeks. While each opposing Army and Navy fought an inglorious holding campaign, the respective Air Forces would dismantle their enemies' country, and if one side did not rapidly surrender, both would be so weak after the first few days that the war would effectively cease. Fighter aircraft would be relegated to spotting patrols, but would be essentially powerless to resist the mighty bombers.
In support of this theory he argued for targeting of the civilian population as much as any military target, since a nation's morale was as important a resource as its weapons. Paradoxically, he suggested that this would actually reduce total casualties, since "The time would soon come when, to put an end to horror and suffering, the people themselves, driven by the instinct of self-preservation, would rise up and demand an end to the war...". As a result of Douhet's proposals airforces allocated greater resources to their bomber squadrons than to their fighters, and the 'dashing young pilots' promoted in propaganda of the time were invariably bomber pilots.
Pre-war planners, on the whole, vastly overestimated the damage bombers could do, and underestimated the resilience of civilian populations. The speed and altitude of modern bombers, and the difficulty of hitting a target while under attack from improved ground fire and fighters which had yet to be built was not appreciated. Jingoistic national pride played a major role: for example, at a time when Germany was still disarmed and France was Britain's only European rival, Trenchard boasted, "the French in a bombing duel would probably squeal before we did". At the time, the expectation was any new war would be brief and very savage. A British Cabinet planning document in 1938 predicted that, if war with Germany broke out, 35% of British homes would be hit by bombs in the first three weeks. (This type of expectation should be kept in mind when considering the conduct of the European leaders who appeased Hitler in the late 1930s.)
Douhet's theories were successfully put into action in Mesopotamia (modern-day Iraq) where RAF bombers used conventional bombs, gas bombs, and strafed forces identified as engaging in guerrilla uprisings. Arthur Harris, a young RAF squadron commander (later nicknamed "Bomber"), reported after a mission in 1924, "The Arab and Kurd now know what real bombing means, in casualties and damage. They know that within 45 minutes a full-sized village can be practically wiped out and a third of its inhabitants killed or injured".
In reality, RAF forces took great care when striking at targets. RAF directives stressed:
In these attacks, endeavour should be made to spare the women and children as far as possible, and for this purpose a warning should be given, whenever practicable. It would be wrong even at this stage to think that air power was simply seen as a tool for rapid retribution.
A statement clearly pointed out that the ability of aircraft to inflict punishment could be open to abuse:
Their power to cover great distances at high speed, their instant readiness for action, their independence (within the detachmentradius) of communications, their indifference to obstacles and the unlikelihood of casualties to air personnel combine to encouragetheir use offensively more often than the occasion warrants.
In strikes over Yemen in over a six month period, sixty tons of bombs were dropped in over 1,200 hours of flying. By August 1928, total losses in ground fighting and air attack, on the Yemeni side, were 65 killed or wounded (one RAF pilot was killed and one airman wounded). Between the wars the RAF conducted 26 separate air operations within the Aden Protectorate. The majority were conducted in response to persistent banditry or to restore the Government's authority. Excluding operations against Yemeni forces – which had effectively ceased by 1934 – a total of twelve deaths were attributed to air attacks conducted between 1919 and 1939. Bombing as a military strategy proved to be an effective and efficient way for the British to police their Middle East protectorates in the 1920s. Fewer men were required as compared to ground forces.
The strategic bombing conducted in World War II was unlike anything the world had seen before. The campaigns conducted in Europe, in China and at the end of the war over Japan, could involve thousands of aircraft dropping tens of thousands of tons of munitions over a single city.
Strategic-bombing campaigns were conducted in Europe and Asia. The Germans and Japanese made use of mostly twin-engined bombers with a payload generally less than 5000 pounds, and never produced larger craft to any great extent. By comparison, the British and Americans (who started the war with predominantly similarly-sized bombers) developed their strategic force based upon much larger four-engined bombers for their strategic campaigns. The payload carried by these planes ranged from 4000lb for the B-17 Flying Fortress on long-range missions, to 8000lb for the B-24 Liberator, 14000lb for the Avro Lancaster, and 20000lb B-29 Superfortress, with some speciality aircraft, such as the 'Special B' Avro Lancaster carrying (22000lb) Grand Slam.
During the first year of the war in Europe, strategic bombing was developed through trial and error. The Luftwaffe had been attacking both civilian and military targets from the very first day of the war, when Germany invaded Poland on 1 September 1939. A strategic-bombing campaign was launched by the Germans as a precursor to the invasion of England to force the RAF to engage Luftwaffe and so be destroyed either on the ground or in the air. When that tactic failed, and the RAF won the Battle of Britain, the Germans launched their night time Blitz hoping to break British morale and cow the British into making peace.
Initially, the Luftwaffe raids took place in daylight, then changed to night bombing attacks when losses became unsustainable. The RAF, initially espousing a precision-bombing doctrine, also switched to night bombing, also due to excessive losses. Before the Rotterdam Blitz on 14 May 1940 the British restricted themselves to tactical bombing west of the Rhine and naval installations. The day after the Rotterdam Blitz a new directive was issued to the RAF to attack targets in the Ruhr, including oil plants and other civilian industrial targets which aided the German war effort, such as blast furnaces that at night were self-illuminating. The first RAF raid on the interior of Germany took place on the night of 15/16 May 1940. After the Butt Report (released in September, 1941) proved the inadequacy of RAF Bomber Command training methods and equipment, the RAF adopted an area-attack strategy, by which it hoped to detrimentally affect Germany's war production, her powers of of resistance (by destroying resources and forcing Germany to divert resources from her front lines to defend her air space), and her morale. The RAF dramatically improved its navigation so that on average its bombs hit closer to target.
The United States Army Air Forces adopted a policy of daylight precision bombing for greater accuracy as, for example, during the Schweinfurt raids. That doctrine, which included the fallacious theory that bombers could adequately defend themselves against air attack with their own armament, entailed much higher American losses until long-range fighter escorts (e.g. the Mustang) became available. Conditions in the European theatre made it very difficult to achieve the accuracy that had been possible using the exceptional and top-secret Norden optical bombsight in the clear skies over the desert bombing ranges of Nevada and California. Raids over Europe commonly took place in conditions of very poor visibility, with targets partly or wholly obscured by thick cloud, smokescreens or smoke from fires started by previous raids. As a result, bomb loads were regularly dropped "blind" using dead-reckoning methods little different from those used by the RAF night bombers. In addition, only the leading bomber in a formation normally carried the Norden sight, the rest of the formation dropping their bombs only when they saw the lead aircraft's bombload falling away. Since even a very tight bomber formation could cover a vast area, the scatter of bombs was likely to be considerable. Add to these difficulties the disruptive effects of increasingly accurate anti-aircraft fire and head-on attacks by fighter aircraft and the theoretical accuracy of daylight bombing was often hard to achieve. 
Strategic bombing was initially a way of taking the war into Europe while Allied ground forces were no closer to fighting Germans there than North Africa. Between them, the Allied air forces claimed to be able to bomb "around the clock". In fact, few targets were ever hit by British and American forces the same day, the strategic isolation of Normandy on D-Day and the bombing of Dresden in February, 1945 being exceptions rather than the rule. There were generally no coordinated plans for around-the-clock bombing of any target.
In some cases, single missions have been considered to constitute strategic bombing. The British bombing of Peenemünde was such an event, as was the bombing of the Ruhr dams. The Peenemünde mission delayed Nazi Germany's V-2 program enough it did not become a factor in the outcome of the war.
Strategic bombing in Europe never reached the decisive completeness the American campaign against Japan achieved, helped in part by the fragility of Japanese housing, which was particularly vulnerable to firebombing through the use of incendiary bombs. The destruction of German infrastructure became apparent, but the Allied campaign against Germany only really succeeded when the Allies began targeting oil refineries and transportation in the last year of the war. At the same time, strategic bombing of Germany was used as a morale booster for the Allies in the period before the land war resumed in Western Europe.
If the Imperial Japanese Navy Air Service and the Imperial Japanese Army Air Service frequently used strategic bombing over large Chinese cities such as Shanghai, Guangzhou, Nanjing, and Chongqing, in the Pacific theatre, organized strategic bombing on a large scale by the Japanese seldom occurred. The Japanese military in most places advanced quickly enough that a strategic bombing campaign was unnecessary, and the Japanese aircraft industry was incapable of producing truly strategic bombers in any event. In those places where it was required, the smaller Japanese bombers (in comparison to British and American types) did not carry a bombload sufficient to inflict the sort of damage regularly occurring at that point in the war in Europe, or later in Japan.
The development of the B-29 gave the United States a bomber with sufficient range to reach the Japanese Home Islands from the safety of American bases in the Pacific or Western China. The capture of the Japanese island of Iwo Jima further enhanced the capabilities that the Americans possessed in their strategic bombing campaign. Conventional bombs and incendiary bombs were used against Japan to devastating effect, with greater indiscriminate loss of life in the firebombing of Tokyo in March 1945 than was caused either by the Dresden mission, or the nuclear bombs dropped on Hiroshima or Nagasaki.
The final development of strategic bombing in World War II was the use of nuclear ordnance. On August 6 and 9, 1945, the United States conducted nuclear bombing raids on Hiroshima and Nagasaki. Both cities were destroyed with enormous loss of life and psychological shock. On August 15 the Emperor announced the surrender of Japan, stating:
"Moreover, the enemy has begun to employ a new and most cruel bomb, the power of which to do damage is indeed incalculable, taking the toll of many innocent lives. Should We continue to fight, it would not only result in an ultimate collapse and obliteration of the Japanese nation, but also it would lead to the total extinction of human civilization. Such being the case, how are We to save the millions of Our subjects; or to atone Ourselves before the hallowed spirits of Our Imperial Ancestors? This is the reason why We have ordered the acceptance of the provisions of the Joint Declaration of the Powers."
Nuclear weapons defined strategic bombing during the Cold War. The age of the massive strategic bombing campaign had come to an end. It was replaced by more devastating attacks using improved sighting and weapons technology. Strategic bombing by the Great Powers also became politically indefensible. The political fallout resulting from the destruction being broadcast on the evening news ended more than one strategic bombing campaign.
In the Vietnam War, the strategic bombing of North Vietnam in Operation Rolling Thunder could have been more extensive, but fear by the Johnson Administration of the entry of China into the war (and misapprehension of the nature and technique of strategic bombing) led to restrictions on the selection of targets, as well as only a gradual escalation of intensity.
The aim of the bombing campaign was to demoralize the North Vietnamese, damage their economy, and reduce their capacity to support the war in the hope that they would negotiate for peace, but it failed to have those effects. The Nixon Administration continued this sort of limited strategic bombing during the two Operation Linebacker campaigns. Images such as that of Kim Phuc Phan Thi (although this incident was the result of close air support rather than strategic bombing) disturbed the American public enough to demand a stop to the campaign.
Due to this, and the ineffectiveness of carpet bombing (partly because of a lack of identifiable targets), new precision weapons were developed. The new weapons allowed more effective and efficient bombing with reduced civilian casualties. High civilian casualties had always been the hallmark of strategic bombing, but later in the Cold War, this began to change.
Strategic bombing was entering a new phase of high-intensity attacks, specifically targeting factories taking years and millions of dollars to build.
Strategic bombing in the post–Cold War era is defined by American advances in and the use of smart munitions. The developments in guided munitions meant that the Coalition forces in the First Gulf War were able to use them, although the majority – 93% – of bombs dropped in that conflict were still conventional, unguided bombs. More frequently in the Kosovo War, and the initial phases of Operation Iraqi Freedom of 2003, strategic bombing campaigns were notable for the heavy use of precision weaponry by those countries that possessed them. Although bombing campaigns were still strategic in their aims, the widespread area bombing tactics of World War II had mostly disappeared. This led to significantly fewer civilian casualties associated with previous bombing campaigns, though it has not brought about a complete end to civilian deaths or collateral property damage.
Additionally, strategic bombing via smart munitions is now possible through the use of aircraft that have been considered traditionally tactical in nature such as the F-16 Fighting Falcon or F-15E Strike Eagle, which had been used during Operation Desert Storm, Operation Enduring Freedom and Operation Iraqi Freedom to destroy targets that would have required large formations of strategic bombers during World War II.
Some people refer to such pinpoint destruction of strategic, logistical or communications/command targets as "strategic interdiction" in order to distinguish from the large concentrated use of conventional or nuclear weapons against highly concentrated population centers or industrial targets, which is what "strategic bombing" had traditionally connoted during World War II and the Cold War. That said, such bombing still may have a place, as evidenced during the 2008 South Ossetia war when Russian aircraft attacked the shipbuilding center of Poti.
With the advent of precision-guided munitions, many feel that strategic bombing has once again become a viable military strategy. Exactly how precise precision munitions are is still open to question. However, others predict that 21st century warfare will more often be asymmetrical, and therefore viable strategic bombing options may not exist.
A further question is raised when some see the blurring of strategic and tactical targets and missions, particularly when tactical aircraft are frequently used to carry out strikes on targets with significant strategic importance as a result of technological advances in aircraft design and munition guidance and penetration. For example, tactical strike aircraft such as F-16s were frequently used to destroy command and communications bunkers during Operation Iraqi Freedom while large "strategic" bombers such as the B-1 and B-52 were frequently used to provide sustained close air support at high altitude during Operation Enduring Freedom.
See main article: Aerial bombardment and international law. Air warfare, must comply with laws and customs of war, including international humanitarian law by protecting the victims of the conflict and refraining from attacks on protected persons.
These restraints on aerial warfare are covered by the general laws of war, because unlike war on land and at sea - which are specifically covered by rules such as the Hague Regulations and Protocol I additional to the Geneva Conventions, which contain pertinent restrictions, prohibitions and guidelines—there are no treaties specific to aerial warfare.
To be legal aerial operations must comply with the principles of humanitarian law: military necessity, distinction, and proportionality: An attack or action must be intended to help in the military defeat of the enemy, it must be an attack on a military objective, and the harm caused to civilians or civilian property must be proportional and not excessive in relation to the concrete and direct military advantage anticipated. 
Among the controversial instances of strategic bombing (and it should be noted that there is still significant controversy over whether all of these events even constitute strategic bombing, as opposed to other forms, such as terror bombing or tactical bombing) are:
. harv. Walter J. Boyne. 1994. Clash of Wings: World War II in the Air. Simon & Schuster. New York. 343, 344. isbn?.