For the Soviet diplomat see Alexander Gregory BarmineBar mine L9 is a large rectangular British anti-tank landmine. The bar mine's principal advantage is its long length - a typical anti-tank landmine is circular, and for it to activate a vehicle's wheel or track must actually press on the mine. The vehicle's wheels or tracks actually make up only a small proportion of its total width. To increase the probability of a vehicle striking the mine, the mine's effective trigger width must be increased.
The bar mine allows a 50% reduction in the number of mines in a minefield without reducing its effectiveness. It was reported that it would take 90 sappers 150 minutes to lay a 1,000 yard mine field consisting of 1,250 Mk 7 British anti-tank mines, weighing a total of 17 tonnes. In comparison it would take 30 sappers 60 minutes to lay a 1,000 yard minefield consisting of 655 barmines weighing a total of 7.2 tonnes. 
The long mines could also be laid through a simple plough attached to the rear of a FV432 armoured personnel carrier. Laying circular mines in similar fashion requires a far larger plough and more powerful towing vehicle. The bar-mine laying FV432s were also usually fitted with launchers for the L10 Ranger Anti-Personnel Mine, to make subsequent clearing of the minefield by hand by enemy sappers more difficult.
The mine is made of plastic, and cannot be detected by metal detectors. A metal plate is attached to mines which are intended to be subsequently recovered by friendly forces, usually for training purposes.
The mine entered British service in 1969. A number of sub-variants of the mine exist, designated L9A1 through L9A8. It is currently scheduled to be replaced in British service in 2010.
It is not known whether they have seen service "in anger" with the British Army, other than with small detachments of special forces during the Gulf War of 1991. A number were captured from Kuwaiti Army stocks by the Iraqi Army in 1990, and subsequently used by them in the same conflict. It was reported that they disabled a number of M60 Patton tanks and other armoured vehicles belonging to the United States Marine Corps, even those fitted with mine-clearing ploughs. Unless the plough struck the mine squarely in the centre, the mine would often be rotated into a position in which it would blow up the track and front roller of the tank.