America Divided – The Civil War of the 1960s Practice Test

The main idea here is that the Gulf of Tonkin Resolution gave the president broad authority to escalate U.S. involvement in Vietnam. After the incidents in the Gulf of Tonkin, Congress passed this resolution, which allowed the president to take all necessary measures to defend Southeast Asia and to repel any armed attack against U.S. forces. In practice, that meant the President could expand military actions in Vietnam without a formal war declaration, leading to greater troop deployments and intensified bombing campaigns.

This is why the best answer is escalation of military involvement. The other options don’t fit the resolution’s purpose: it wasn’t a move to withdraw troops, it wasn’t specifically a step to open negotiations, and it wasn’t framed as establishing a naval blockade.