They're merely purchasing our weapons through Israel for fun.
The Harpy drones have no US tech, and their sale had been approved to China in 1999.
They were sent back to Israel for service, and we threatened Israel over repairing them or even just returning them, even though the US approved their sale in '99. Basically they are model airplanes with cameras affixed. Useless in an invasion of Taiwan, unless you can land and protect the people who fly them.