One of the major inciting factors for protests against the war was the invasion of Cambodia on April 28, 1970. Tom Wells, in his book The War Within, describes the buildup to Nixon’s decision to invade Cambodia, as well as the backlash. Before this, the antiwar movement had stayed mainly to the far left of the political spectrum and on college campuses. The general public viewed the demonstrators as unpatriotic dissidents. The Johnson and Nixon administrations relied upon this “silent majority” to support the war effort. However, by April of 1970, the silent majority was losing some of its clout. The white was receiving more and more letters protesting the war, and public opinion over American intervention in Vietnam became increasingly more negative (Wells 410). However, the invasion of Cambodia, which was seen as an unprovoked attack on a peaceful country, sparked outrage among several groups in America, including some people within the white house.
In March of 1970, Nixon began increasing the U.S. military presence in both Cambodia and Laos. On April 22, it was leaked that Nixon had authorized the provision of captured enemy rifles to the Cambodian government, and Nixon was furious. This incident resulted in Nixon ordering lie detector tests for several possible culprits and the firing of several others, including Assistant Secretary of State Marshall Green, who was apparently fired “at least two to three times during the course of his tenure” (Wells 416). Wells paints a picture of an increasingly unstable Nixon in the build up to the invasion. When planning the operation, Nixon left out most of the state and defense departments and ignored the opinions of his advisors. Three aides to the Secretary of State and some consultants resigned over the invasion (Wells 417).
College campuses did not receive the news of the invasion well. One of the white house advisors had warned Nixon that the “campuses would go up in flames” and he was not far off (Wells 417). Student protests sprang up everywhere, and other groups also began to complain about the war effort. Kent State was one of the most famous of these protests. The students there had originally met to protest the invasion into Cambodia peacefully before the violence and rioting broke out, which resulted in the National Guard being called out. Protests over the invasion, combined with outrage over the Kent State Shootings, led to an increasingly negative opinion of the war. It became so extreme that Nixon was forced to put a deadline on the invasion within Cambodia, and incited Congress to propose two amendments to decrease U.S. troops in Vietnam (Wells 426). The invasion and the shootings worked together to create a sense of unease over the war within the general population of the U.S.