After a genuine clash involving USS Maddox off North Vietnam, American ships reported a second attack in the Gulf of Tonkin on 4 August. Confused radar, sonar and radio information was interpreted as hostile action, although the second attack almost certainly did not occur. The reports helped secure congressional authority for a major escalation in Vietnam.

The widening war inspired protest poetry by Denise Levertov, Allen Ginsberg and many others who challenged official language and televised claims. Tonkin became a defining example of how uncertain information could be converted into the rhetoric of military necessity.