The My Lai massacre changed public perception of Vietnam drastically. Many people already thought it was an unjust war, and this added to that anti-war sentiment. When many veterans came home they were treated like trash, because everyone back home saw the terrible war crimes committed by the U.S. Many people called for an end to Vietnam after it.
It made them become hated
The correct answer to this open question is the following.
Although the question does not include statements or options to answer it, we can say that the changes in American foreign policy during the Nixon administration were the following.
The most important was the foreign policy of détente, which try to create some peaceful relations with the Soviet Union during the tense Cold War years in which the Soviet Union tried to spread Communism in different countries and the United States tried to stop it.
Indeed, Richard Nixon made an official visit to Moscow in May 1972, to have a meeting with Soviet Union leader Leonid Brezhnev. They signed the SALT Treaty (the Strategic Arms Limitation Treaty). Previously, in February 1972, President Nixon had visited China to improve foreign relations with this Communist country.
