To enhance his chances for election, [Johnson] and McNamara deceived the American people and Congress about events and the nature of the American commitment in Vietnam. They used a questionable report of a North Vietnamese attack on American naval vessels to justify the president's policy to the electorate and to defuse Republican senator and presidential candidate Barry Goldwater's charges that Lyndon Johnson was irresolute and "soft" in the foreign policy arena.
https://www.usni.org/magazines/naval-history-magazine/2008/february/truth-about-tonkinEdited by Spanky at 10:21:11 on 03/23/21