Introduced in 1955, the B-52 of Dr Strangelove fame was designed as the mainstay of the USA's long-range nuclear bomber force, but has been used in anger to drop conventional weapons.
In the Gulf War, B-52s dropped 40% of all coalition bombs. Carrying air-launched cruise missiles, they opened the attack on Yugoslav forces in the Kosovo campaign.
The bomber is almost 160 feet (49 metres) long with wings spanning 185 ft (56 m), eight turbofan jet engines slung under them in four pairs.
Top speed is only about 630mph (1,014 kph) but the B-52 has a range without refuelling of more than 8,000 miles (12,870 kms) with a 10,000 lb (4,536 kg) bomb load and can fly high, up to 50,000 ft (15,240 m).
It could also fly low, using terrain-mapping radar showing the ground up to 10 miles ahead of the aircraft - but this role has been dropped. The pilots wear night vision goggles to see in the dark.
There are six crew places on two decks but on the current version there are only five crew, since the job of rear gunner was dropped: Commander, co-pilot and electronic warfare officer, navigator and radar navigator, who delivers the weapons.
In its internal, 28 ft-long weapons bay and on pylons beneath the wings the current H version can carry a wide mix of bombs and missiles, such as 51, 500 lb (227 kg) bombs, 30 cluster bombs, or 20 cruise missiles.
The United States has 44 B-52s in constant readiness for combat use and the aircraft is expected to continue in service for another 40 years.