Social Studies - The legal basis for the escalation of United States involvement in the Vietnam War was the

The legal basis for the escalation of United States involvement in the Vietnam War was the 

(A) declaration of war by Congress 

(B) passage of the Gulf of Tonkin Resolution by Congress 

(C) United Nations resolution condemning the North Vietnamese invasion of South Vietnam 

(D) mutual defense provisions of the North Atlantic Treaty Organization (NATO)

Answer: 

Option (B) is correct. 

There was no declaration of war by Congress. However, Congress did pass the Gulf of Tonkin Resolution, which authorized the president to “take all necessary measures to repel any armed attack against the forces of the United States and to prevent further aggression.”