How did us involvement in vietnam change over time? select all that apply. the united states sent more and more troops to vietnam in the 1960s. the united states turned over defense of south vietnam to the south vietnamese army. the united states took over the defense of south vietnam. the gulf of tonkin incident led the united states to declare war on north vietnam. the gulf of tonkin resolution gave the president more authority to get involved in vietnam.

The correct answers are: The United States sent more and more troops to Vietnam in the 1960s, The United States took over the defense of South Vietnam and The Gulf of Tonkin Resolution gave the president more authority to get involved in Vietnam.

       During the early 1960s South Vietnam was at risk of infiltration and invasion by communists hence the US government and aimed to stop Soviet influence over South Vietnam. The South Vietnamese military had grown and developed considerably but was still incapable of defending the new nation thus the US sent more troops to Vietnam.

The attacks in the Gulf of Tonkin spur Congress passed the Gulf of Tonkin Resolution which authorizes the president to take all necessary measures that included the use of armed force against any aggressor in the conflict.

d: social contract theory