Lee ran as the incumbent in Taiwan's first direct presidential election in 1996 against DPP candidate and former dissident, Peng Min-ming. This election prompted the PRC to conduct a series of missile tests in the Taiwan Strait to intimidate the Taiwanese electorate so that electorates would vote for other pro-unification candidates, Chen Li-an and Lin Yang-kang. The aggressive tactic prompted U.S. President Clinton to invoke the Taiwan Relations Act and dispatch two aircraft carrier battle groups into the region off Taiwan's southern coast to monitor the situation, and PRC's missile tests were forced to end earlier than planned. This incident is known as the 1996 Taiwan Straits Crisis.