Since Bill Clinton assumed office in the White House, the U.S. government has made several adjustments of its Taiwan policy, the latest one took place after Li Tenghui issued the statement on July 9,1999 about the so called “state to state relationship” between the mainland and Taiwan. To prevent the situation from precipitating into a crisis in the Sino U.S. relationship, American government took some measures of “preventive diplomacy.” However, with increased pressure from conservative forces at home, the U.S. Congress passed a series of pro Taiwan, anti PRC resolutions, representing the duality in U.S. Taiwan policy.