GIs to get missile interceptors

American troops in Bosnia are to be protected by a backpack device which uses radio waves to detonate incoming artillery and mortar shells prematurely, writes Christopher Bellamy.

The United States Army intends to field the Shortstop electronic protection system to defend airfields, barracks, command posts and US forces on patrol later this year, according to Jane's Defence Weekly.

The lightest variant of the system weighs 25lb to 30lb and can be carried in a backpack. There are also 50lb and 100lb devices, which can be mounted in vehicles or in static positions. Nine of these units, costing about $60,000 (pounds 39,400) each, will be delivered later this year.

The incoming shells which Shortstop is designed to counter use a reflected radio signal to make them explode about 30 feet above the ground.

The Americans discovered the idea by accident in the Second World War, during the Battle of the Bulge, when in their desperation the American troops fired everything they had - including very expensive anti-aircraft shells - at the German ground troops. The shells exploded at the most lethal possible height above the ground. Shortstop captures the signal from the incoming shell and throws it back, tricking it into detonating as much as 800 metres (half a mile) from the target it is protecting.

However, the trouble is that the warring factions in Bosnia are not nearly as sophisticated as the Americans.

Nevertheless, the United States forces believe that Shortstop will protect key targets against the deadliest shells and mortar bombs that the former warring factions might use.