J-20 stealth fighters make a flight demonstration during an activity celebrating the 70th founding anniversary of the Chinese People's Liberation Army (PLA) air force in Changchun, capital of northeast China's Jilin Province, Oct. 17, 2019. It's the first time that J-20 stealth fighters and Y-20 transport aircrafts make a flight demonstration at the northeastern China during the activity. (Xinhua/Lin Hong)
