Legality of the Vietnam War

The Gulf of Tonkin Resolution, passed in 1964, authorized U.S. President Lyndon B. Johnson to use military force in Southeast Asia. The Resolution was repealed in 1971, however, and President Richard M. Nixon cited his power as commander-in-chief of U.S. forces under Article Two of the United States Constitution as legal authority for operations in Vietnam. No formal declaration of war was ever made, a violation of the US Constitution according to many.

Question: was there congressional approval for the vietnam war
Answer: no