Vietnam ground combat operations in 1965, and at their peak they numbered more than 500,000. The US also engaged in a sustained aerial bombing campaign. Meanwhile, China and the Soviet Union provided North Vietnam with significant material aid and 15,000 combat advisers. Communist forces supplying the Việt Cộng carried supplies along the Hồ Chí Minh trail, which passed through the Kingdom of Laos. The communists attacked South Vietnamese targets during the 1968 Tết Offensive. Although the campaign failed militarily, it shocked the American establishment, and turned US public opinion against the war. During the offensive, communist troops massacred over 3,000 civilians
China in the Vietnam War the revolution deeper into Southeast Asia via the Indochinese internationalist model. Then relations changes in the late 1960s, as the Cultural Revolution and Maoist visions of permanent revolutionary struggle ran up against important and extremely complex geostrategic differences in Vietnam in the war against the US. Nonetheless, the Chinese continued to supply massive amounts of military and economic aid, as well as sending over 300,000 military support troops into northern Vietnam. Internationalism did suffer a serious blow, plus the Sino-Soviet split, which brought damage to the relations between China, the Soviet Union and of course, Vietnam. Vietnam War: https://en.wikipedia.org/wiki/Vietnam_War First