No, Congress was not justified to go to war over the Gulf of Tonkin incident in which US warships were fired on by North Vietnamese forces. Vietnam was only artificially divided by the French into north and south but historically it had always before been one country. |North Vietnam had every right to fire on US warships in its territorial waters which were a provocation. Think if a superpower like China or the Soviet Union had warships just off the US coast what the effect would be.
