After the People’s Republic of China captured the Paracel Archipelago in 1974, and in 1976 a single Vietnamese state appeared on the world map, the contradictions between the People’s Republic of China and Vietnam were heated up to the limit, the air smelled of war.
In addition, by the beginning of the 1970s, once warm relations between the “brothers forever”, the USSR and China, had finally turned into cold ones. This split the once united camp of socialism.
Realizing his plans, Mao Zedong etched out from the memory of the Chinese what help the USSR provided to their country. Although, many remembered this.
Mao Zedong’s policies bore fruit; supporters of Soviet-Chinese friendship in the CCP were repressed, expelled, arrested, or killed.
The state pursued a policy of demonization of the USSR, of pre-revolutionary – tsarist Russia. They accused her of constant aggression, the seizure of “Chinese” territories, etc. etc.
And Mao Zedong gathered enormous power in the hands of the party and state.
For reference: in China, the highest position is the Secretary General of the CPC Central Committee – the Central Committee of the Chinese Communist Party (from 1943 to 1982 – Chairman of the CPC Central Committee).
But at meetings with foreign leaders, for example, the incumbent head of state, Xi Jinping, introduces himself as Chairman of the PRC.
Also, the PRC’s actions led to armed clashes with the USSR in 1969, on Damansky Island and near Lake Zhalanashkol.
It is not surprising that the USSR and the socialist Vietnam, which survived thanks to his help, became closer.
Vietnam, on the other hand, was subject to strong pressure from the PRC in all spheres – the economy, diplomacy, etc. Among about 1 million Chinese living in Vietnam, underground organizations were set up to collect information and sabotage.
After the Vietnamese forces overthrew the pro-Chinese Khmer Rouge regime in Kampuchea (Cambodia) in 1978, this provoked a sharp reaction from the PRC, looking for a reason to “deal” with Vietnam.
For reference: Pol Pot and his Khmer Rouge established such a regime in Cambodia that they outdid many in their cruelty.
With the support of the PRC and Chinese “advisers,” Pol Pot and his associates launched a series of crazy “experiments” in Kampuchea, which essentially resulted in genocide against their own people. According to various estimates, from 1 to 3 million people died as a result of the construction of “agrarian socialism”.
The Khmer Rouge is China’s counterbalance to Vietnam’s influence, and Vietnam is the USSR’s counterbalance to China’s influence.
Although all 3 states: the USSR, China and Vietnam are communist.
Therefore, ideology is ideology, and the goals and interests of all are different.
Taking advantage of the fact that the most combat-ready units of the Vietnamese troops were in Cambodia (until 1989), the PRC invaded Vietnam in the spring of 1979. The number of Chinese invasion forces was about 250 thousand people, Vietnamese – about 100 thousand.
But, to the surprise of the Chinese leaders, headed by Deng Xiaoping, the Vietnamese put up stubborn resistance, which led to the disruption of the plans of the Chinese command.
This was largely due to the fact that the people of Vietnam, who stood up against the French and Americans, were ready to stand up for their independence. Many units had serious combat experience. Unlike the Chinese noobs.
Then, under pressure from the USSR, hostilities subsided, although skirmishes continued until the end of the 1980s.
As a result, China, after all, seized the territory in the north and part of the Spratly Islands from Vietnam.