In 1965 president johnson immediately used the authority of the gulf of tonkin resolution to

Begin sustained bombing of North Vietnam. Hope this helps! :D

Sustained bombing of North Vietnam is the correct answer.

Explanation:

The Gulf of Tonkin resolution was enacted on August 10, 1964. It was a joint resolution which was passed by the United States Congress in response to the Gulf of Tonkin incident. The resolution is of historic significance it gave President Lyndon B. Johnson the authority for the use of the military in Southeast Asia without a formal declaration of war. It allowed the president to take necessary steps for assisting the member and protocol states of the Southeast Asia Collective Defense Treaty. This resolution was opposed by two senators only. It led to the bombing of North Vietnam by US.