How did American foreign policy change as a result of involvement in Vietnam?

Part of
America's change in foreign policy was a willingness to use special operations soldiers in
advancing American interests. In an attempt to drive out the Viet Cong from the Ho Chi Minh
Trail, the United States invaded Laos and Cambodia. The Viet Cong were still able to use the
trail, and the American invasion destabilized these two countries, thus making the postwar
refugee situation worse.

As a result of Vietnam, the American people did
not...