A high-altitude surveillance aircraft which first flew in 1955 and figured prominently in the Cold War. It is still invaluable to military commanders.
The U-2 was developed as a CIA project to photograph Soviet military facilities. To do so, U-2s were based in great secrecy at Adana in Turkey - later renamed the Incirlik airbase - and operated out of Pakistan.
That was until 1960, when a U-2 was shot down by a volley of Soviet surface-to-air missiles. The pilot, Gary Powers, ejected but was captured and held for two years on spying charges.
It was also a U-2 that showed Soviet missiles being put into Cuba in October 1962. Another was shot down on a similar mission shortly afterwards. Another five have been brought down over China.
The aircraft is long and thin, with wings 100 feet (30.5 metres) across that are more like those of a glider. Landing is so difficult that it requires advice from a second pilot in a chase car that follows the U-2 along the runway.
Later U-2S versions are bigger and the single engine has been updated to be more powerful but also more economical.
It flies at less than 500 mph (805 kph), but its significance as a reconnaissance aircraft is that it can cruise at up to 90,000 ft (27,430 m) - more than 17 miles (27 km) up and so high that the single pilot has to wear a space suit. It is a very uncomfortable flying environment.
The U-2S has interchangeable noses and an equipment bay that allow it to carry different sensors for a variety of roles such as photographic, electro-optic, infrared and radar.
There are thought to be 31 in service, based in the United States, France, Cyprus, Saudi Arabia and South Korea.