Why Russia accused China of copying its stealth fighter design

It's not uncommon to hear people citing China's theft of American F-22 and F-35 plans as inspiration for its J-20 stealth fighter, but Russia has also raised suspicions about China borrowing heavily from one of its own defunct fighter efforts. The Chengdu J-20 Mighty Dragon is China's first fifth-generation fighter, with roots dating back to the nation's J-XX program that began in the late 1990s.

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