Why does Johnson claim that North Vietnam deliberately attacked the U. S.?

This answer relates to The Gulf Of Tonkin Resolution.

Explanation:

In 1964 the American government claimed that their ships had been attacked in the Gulf of Tonkin in international waters by the North Vietnamese. These attacks it was claimed, were unprovoked.

American presidents have to have a two-thirds majority in the Senate to declare war. These claims, which were later disproved, led to the Gulf of Tonkin resolution which, in effect, gave Johnson a carte blanche in terms of American involvement in Vietnam, thereby bypassing any need for a formal declaration of war.

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