During that decade, the international system changed fundamentally after the Cold War, and so did Sino-U.S. relations, which were worsened by differences and contradictions. The U.S. government decided to sell weapons to Taiwan in September 1992, and permitted Taiwan leader Li Deng-hui to visit the United States in May 1995. The Taiwan Straits Crisis the following year presented the biggest challenge to Sino-U.S. relations.