Sino - Vietnamese conflicts 1979 – 90 The Sino - Vietnamese conflicts of 1979 – 1990 were a series of border clashes between the People ' s Republic of China and the Socialist Republic of Vietnam following the Sino - Vietnamese War in 1979 . These border clashes lasted from the end of the Sino - Vietnamese War in 1979 until 1990 . When Chinese troops withdrew from Vietnam in March 1979 after the war , China announced that they were not ambitious for " any square inch of the territory of Vietnam " . In fact , Chinese troops occupied an area of 60 km , which was disputed land controlled by Vietnam before hostilities broke out . In some places such as the area around Friendship Gate in Lạng Sơn Province , Chinese troops occupied territories which have no military value but important symbolic value . Elsewhere , Chinese troops occupied the strategic positions of military importance as a springboard to attack Vietnam . These areas , arguably , have always been considered as part of China despite of their actual control by Vietnam . The Chinese occupation of border territory angered Vietnam , and this ushered in a series of fights between the two sides to gain control of the area . Border conflicts between Vietnam and China continued until 1988 , peaking in the years 1984 – 1985 . By the early 1990s , along with the withdrawal of Vietnam from Cambodia and the collapse of the Soviet Union , the relationship between the two countries gradually returned to normality . Background . Since 1979 , there were at least six big rounds of clashes on the Sino - Vietnamese border , in June 1980 , May 1981 , April 1983 , April 1984 , June 1985 and December 1986 - January 1987 . According to Western observers , all were initiated or provoked by the Chinese to serve their political objectives . Shelling of Cao Bang . Since early 1980 , Vietnam conducted military operations in the dry season to sweep small Khmer Rouge forces over the Cambodian - Thai border so that they would not be in Vietnamese - occupied Cambodia . To put pressure on Vietnam to withdraw military forces from Cambodia , China created pressure on the Sino - Vietnamese border by deploying troops there . China conducted military training for some 5 , 000 anti - Laotian H ' mong troops in Yunnan Province and used these force to attack Muong Sing in northwest Laos near the Sino - Laotian border . Vietnam responded by increasing forces stationed at the Sino - Vietnamese border , and China no longer had the advantage of forces as they did on their campaign in February 1979 . In June 1980 , Vietnamese troops crossed the Thai - Cambodian border into Thai territory during the pursuit of defeated Khmer Rouge to Thai territory . Despite rapid Vietnamese withdrawal from Thai territory , the Vietnamese incursion made China feel they must act to support their allied Thailand and the Khmer Rouge . On the days from June 28 to July 6 , in addition to outspoken criticism of Vietnam in diplomatic announcements , the Chinese troops continuously shelled Cao Bằng Province in northern Vietnam . The Chinese shellings did not aim at any strategic military target at all , nor did these shellings create any substantial damage on Vietnam but was symbolic . Vietnam felt the conduct of military operations on a large scale was beyond the Chinese capabilities , so Vietnam could have a free hand to conduct military operations in Cambodia . However , Chinese shellings had shaped the types of conflict on the Sino - Vietnamese border in the next 10 years . Johnson South Reef Skirmish . On March 14 , 1988 , a naval battle was fought between Vietnam People ' s Navy and People ' s Liberation Army Navy at the Spratly Islands . The battle resulted in the death of 64 Vietnamese soldiers and since then , China has controlled the Johnson South Reef of the Spratly Islands .