Communist North Vietnam Democratic Republic of Vietnam (DRV)
Communist Viet Cong National Liberation Front (NLF)
Communist China People's Republic of China (PRC)
Newly communist China had supported Ho Chi Minh during the war with the French, and continued to do so during the war with the U.S. by providing weapons, expertise and manpower. Despite being in bad economic shape at the time, newly Communist China aided Ho during the war with the French, and did so again during the war with the Americans, providing weapons, expertise, and manpower. All told, the Chinese claimed to have spent over $20 billion in support of North Vietnam and deployed 320,000 military personnel, more than 4,000 of whom died.
POSTER ENTITLED "SUPPORT VIETNAM PEOPLE," CIRCA 1969, SHOWING CHINA'S SUPPORT OF THE COMMUNIST CAUSE IN VIETNAM. For the most part, the Chinese stayed in the background, rebuilding areas destroyed by U.S. bombs and manning anti-aircraft batteries. But perhaps their biggest role was preemptive: They made it clear that if U.S. ground troops invaded North Vietnam, then they would respond in kind. Unlike during the Korean War, the United States yielded to this threat. “Their function is as a tripwire,” Moise says, “a warning to the Americans: ‘Don’t go too far… or you’ll be fighting us.’” China and the Soviet Union didn’t have to do as much as the Americans, Moise explains, because they were buttressing the stronger side. Nonetheless, “if there had been no Chinese or Soviet support, the North Vietnamese could not have won,” he says, pointing out that the U.S. military budget was roughly 30 times greater than the entire gross national product of North Vietnam. https://www.history.com/news/vietnam-war-combatants#section_7
Soviet Union Union of Soviet Socialist Republics (USSR)
As the original communist state, the Soviet Union aided North Vietnam, with increasing support in the late 1960s. While the U.S.S.R. supplied some troops, their biggest contribution was in weaponry. Though it originally took little interest in the Vietnam War, the Soviet Union secretly ramped up its aid to North Vietnam following Nikita Khrushchev’s fall from power. The Soviets wanted to “make life difficult for the United States,” McAllister says, “but they didn’t want to do it in a way that got them in a conflict with the United States.” Soviet involvement in the war increased in the late 1960s, just as China’s influence was lessening. (The two countries were undergoing a bitter split at the time.)
SOVFOTO/UNIVERSAL IMAGES GROUP/GETTY IMAGES A COLD WAR-ERA BILLBOARD IN MOSCOW SHOWING BOMBS RAINING DOWN ON UNCLE SAM READING, '<EM>AGGRESSORS OUT OF VIETNAM!' IN </EM>1968.Among other weapons, the USSR provided surface-to-air missiles that the Chinese weren’t yet technologically capable of producing. The Soviets even allegedly shot down some U.S. planes. Overall, though, they pumped only about 3,000 troops into the conflict, far fewer than the Chinese. https://www.history.com/news/vietnam-war-combatants#section_7
North Korea Democratic People's Republic of Korea (DPRK)