The background of the self-defense and counterattack war against Vietnam is a complex and delicate international political environment, which is part of the triangular game between China, the United States and the Soviet Union. Vietnam's ingratitude and betrayal, as well as China's intolerability and justice, together constituted the cause of the war. 
In the process of helping Vietnam, China did not hesitate to confront France, the United States and other Western countries. China sent hundreds of thousands of volunteers, transported large quantities of military supplies, and even sacrificed its own national interests. According to statistics, from 1950 to 1975, China provided nearly $30 billion in aid to Vietnam, equivalent to half of China's national income at that time. China has built 450 complete sets of projects for Vietnam, including electricity, transportation, communications, industry, agriculture and other fields. These projects have played a vital role in Vietnam's economic development and social progress. China has also trained hundreds of thousands of technicians and cadres for Vietnam, providing strong talent support for Vietnam's development. It can be said that without the support of China, there would have been no victory for Vietnam. 
At the end of 1970, in order to force North Vietnam to the negotiating table, the United States again escalated the Vietnam War. This time China's performance is very "intriguing". On the one hand, China still unequivocally supports the Vietnamese people in opposing US aggressionOn the other hand, China has also begun to actively promote exchanges with the United States and invited Nixon to visit China. Despite repeated statements to Vietnamese leaders that China will continue to support Vietnam, Sino-US contacts have caused a "strong **" from Vietnam's point of view, which is very worried that they will become a "bargaining chip" and be "sold" by China. Vietnam's fears are not unfounded. Since Nixon's visit to China, although there are still many contradictions between China and the United States, and the road to establishing diplomatic relations is also full of bumps, the two sides have begun to have a lot of consensus and cooperation on the grand strategy of "dealing with the Soviet Union." This trend has left Vietnam feeling uneasy and lost. In August and September 1975, when the newly reunited Vietnam was in ruins, the top leaders of the Communist Party of Vietnam, Le Duc Tho and Le Duan, visited Beijing in the hope of receiving Chinese assistance. However, Le Duc Tho returned empty-handed, and the seriously ill *** said to him: "You Vietnamese have to let us take a breath and recover." The latter, in turn, received a reply from the "Gang of Four", demanding that Vietnam publicly condemn Soviet hegemony – a categorical rejection of Vietnam's demands.
Li Duan came to Moscow with a stomach full of anger, and was warmly received by Brezhnev and promised assistance.
Subsequently, Vietnam refused to recognize China's territorial claims, and instead colluded with the Soviet Union to illegally occupy some of China's islands in the South China Sea, including the Xisha Islands and Nansha Islands, seriously violating China's sovereignty and maritime rights and interests. Vietnam has frequently caused incidents on the Sino-Vietnamese border, harassed and attacked Chinese border guards, and even shot Chinese border guards, causing losses to Chinese personnel and property. 
Vietnam, with the support of the Soviet Union, began its invasion and intervention in Cambodia, overthrew Cambodia's democratically elected **, established a puppet regime, ** Cambodia's innocent people, and triggered a humanitarian crisis in Cambodia. Vietnam confronted China internationally, opposed China's reform and opening up policy, slandered China's socialist system, undermined China's international image, hindered China's diplomatic development, and together with the Soviet Union, attempted to isolate and encircle China. Vietnam's actions have seriously violated China's bottom line and aroused China's anger. China has repeatedly put forward proposals for a peaceful settlement to Vietnam, demanding that Vietnam stop its provocations and aggression against China, withdraw from China's territory, stop interfering in Cambodia, and restore friendly relations between China and Vietnam. However, Vietnam not only did not listen to China's advice, but became even more arrogant and arrogant, continued to provoke and invade China, and even threatened to wage war against China to fight China back before liberation. Unable to bear it any longer, China decided to launch a powerful counterattack against Vietnam as a warning and punishment, but also to safeguard its own national interests and security, as well as peace and stability in the Indochina Peninsula. On January 1, 1979, China and the United States formally established diplomatic relations, China's international status has been greatly enhanced, China's international environment has also been greatly improved, and China's national security has also been greatly guaranteed. 
On February 17, 1979, China launched a self-defense counterattack against Vietnam after making full preparations. This is a war to maintain the dignity of the country and protect the strength of the country. With a thunderous force, the squadron quickly broke through the Vietnamese defense line and destroyed military facilities and lines of communication in northern Vietnam.