American Volunteer Group in China (1941–1942)
About 100 U.S. military pilots resigned their commissions to fly P-40s for China against Japan, months before Pearl Harbor brought the United States into the war. Officially they were civilian volunteers; in practice, the Roosevelt administration approved the unit and supplied the aircraft.
The 'Flying Tigers' claimed roughly 300 Japanese aircraft destroyed before being absorbed into the U.S. Army Air Forces in July 1942.
Washington's role was eventually acknowledged and the unit became a celebrated piece of U.S. air history. The episode is a textbook case of plausible-deniability military aid that later turned into open alliance.
AVIC engineers at Pakistani airbases play the same role the AVG played in 1941: skilled foreign personnel directly enabling a client's combat operations under a thin civilian label. Beijing's choice to publicize the involvement after the fact mirrors how the U.S. eventually claimed the Flying Tigers.