<Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> <P> By 1967, the rationale for what had become a costly U.S. involvement In the Vietnam War was receiving close scrutiny . With opposition to the war mounting, a movement to repeal the resolution--which war critics decried as having given the Johnson administration a "blank check"--began to gather steam . </P> <P> An investigation by the Senate Foreign Relations Committee revealed that Maddox had been on an electronic intelligence collection mission off the North Vietnamese coast . It also learned that the U.S. Naval Communication Center in the Philippine Islands, in reviewing ships' messages, had questioned whether any second attack had actually occurred . </P> <P> The administration of President Richard Nixon, which took office in January 1969, initially opposed repeal, warning of "consequences for Southeast Asia (that) go beyond the war in Vietnam". In 1970 the administration began to shift its stance . It asserted that its conduct of operations in Southeast Asia was based not on the resolution but was a constitutional exercise of the President's authority, as Commander in Chief of U.S. military forces, to take necessary steps to protect American troops as they were gradually withdrawn (the U.S. had begun withdrawing its forces from Vietnam in 1969 under a policy known as "Vietnamization"). </P>

What event causes the senate to repeal the tonkin gulf resolution
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