To date, the B-2 Spirit is considered the most expensive aircraft ever built. It is expensive to the point that in 1987, Congress was forced to cut orders from 132 to 21 units. After the accident in 2008, at present, only 20 units are operating under the control of the United States Air Force. Aircraft bombed this strategy allows the use of nuclear weapons and conventional weapons. Strategy B-2 has been used in the war in Iraq and Afghanistan