I don't think the goal of the Chinese war with Vietnam was to invade and occupy the country.
It was about the Vietnamese invading Cambodia, which was not as bad as it sounds, since Cambodia was being run by Pol Pot and the Kn=hmer Rouge, that for some reason, were allied with the Societs.
The Sino-Vietnamese War (Vietnamese: Chi?n tranh biên gi?i Vi?t-Trung; simplified Chinese:
?; traditional Chinese:
?; pinyin: Zh?ng-Yuè Zhànzh?ng), also known as the Third Indochina War, was a brief border war fought between the People's Republic of China and the Socialist Republic of Vietnam in early 1979. China launched the offensive in response to Vietnam's invasion and occupation of Cambodia in 1978 (which ended the rule of the Chinese-backed Khmer Rouge).[14] Chinese leader Deng Xiaoping saw this as a Soviet attempt "to extend its evil tentacles to Southeast Asia and...carry out expansion there", which reflected the long-standing Sino-Soviet split.[15] As the former U.S. Secretary of State Henry Kissinger noted that "[w]hatever the shortcomings of its execution, the Chinese campaign reflected a serious, long-term strategic analysis".[16]
The Chinese entered northern Vietnam and captured some of the cities near the border. On March 6, 1979, China declared that the gate to Hanoi was open and that their punitive mission had been achieved. Chinese forces retreated back across the Vietnamese border into China. Both China and Vietnam claimed victory in the last of the Indochina Wars of the 20th century; as Vietnamese troops remained in Cambodia until 1989, it can be said that China failed to achieve the goal of dissuading Vietnam from involvement in Cambodia. Following the dissolution of the Soviet Union, the Sino-Vietnamese border was finalized.
China demonstrated to its Cold War Communist adversary, the Soviet Union, that they were unable to protect their new Vietnamese ally.[17] Following worsening relations between the Soviet Union and China as a result of the Sino-Soviet split, as many as 1.5 million Chinese troops were stationed along the Soviet-Chinese border, in preparation for a full-scale war.
