When Vietnam fought back against the United States, China did give Vietnam a lot of help, but not as much as the Soviet Union. It can be said that the former Soviet Union is the biggest supporter of Vietnam's anti-American war, and China can only rank second. China's help to Vietnam is not entirely out of noble feelings, but also out of practical needs. Because once Vietnam is occupied by American troops, life in China will naturally be very hard. Therefore, after Vietnam defeated the US military, it naturally put the former Soviet Union in the first place and China in the second place.
Soon after, the relationship between China and the former Soviet Union deteriorated. Naturally, Vietnam followed Big Brother and became hostile to China.
In the 1980s, China began its honeymoon with the United States, and China naturally helped the United States deal with the former Soviet Union. The former Soviet Union was strong and could not attack directly, but Vietnam could attack. So Vietnam became the shield of the former Soviet Union. Through China's self-defense counterattack against Vietnam, the international influence and status of the former Soviet Union were lowered, which made the former Soviet Union hold its head in front of the younger brother of the world and paid a high price for this war. After the Vietnam War, the international power of the former Soviet Union began to shrink in an all-round way, and then the United States sent troops to Iraq in the Middle East, and the international power of the former Soviet Union was further reduced. The United States also completed the layout of Asia through China's self-defense counterattack against Viet Nam. It was only after the United States and China turned against each other that China discovered that he had been played by the United States. So up to now, the self-defense counterattack against China has become a dark side in its history, and everyone tries not to mention it.