"What does IDF stand for?" the joke begins. "I don't fly," is the punch line. The correct answer is the Indigenous Defense Fighter, but the witticism reflects a certain lack of confidence in Taiwan's national defense program. From the moment Washington severed diplomatic ties with Taipei in favor of Beijing in 1979, the Taiwanese have had much to feel nervous about. "The international climate changed," says James Mao, director of the Executive Office of the Aero space Industrial Development Corporation (AIDC). "It became more and more difficult to purchase planes from the United States, especially fighter jets."