Chinese officials recently unveiled a new, high-tech stealth fighter that could pose a significant threat to American air superiority - and some of its technology, it turns out, may well have come from the US itself.
Balkan military officials and other experts have said that in all probability the Chinese gleaned some of their technological know-how from an American F-117 Nighthawk that was shot down over Serbia in 1999.
Nighthawks were the world's first stealth fighters, planes that were very hard for radar to detect. But on March 27, 1999, during NATO's aerial bombing of Serbia in the Kosovo war, a Serbian anti-aircraft missile shot one of the Nighthawks down. The pilot ejected and was rescued.