China has posed a far more serious challenge to Vietnam's national security since the Second Indochina War, especially because of its twenty-nine-day incursion into Vietnam in February 1979, which, according to the Vietnamese, has continued as a "multifaceted war of sabotage." China's 1979 invasion was a response to what China considered to be a collection of provocative actions and policies on Hanoi's part. These included Vietnamese intimacy with the Soviet Union, mistreatment of ethnic Chinese ( Hoa--see Glossary) living in Vietnam, hegemonistic "imperial dreams" in Southeast Asia, and spurning of Beijing's attempt to repatriate Chinese residents of Vietnam to China. The Chinese attack came at dawn on the morning of February 17, and employed infantry, armor, and artillery. Air power was not employed then or at any time during the war. Within a day, the Chinese People's Liberation Army (PLA) had advanced some eight kilometers into Vietnam along a broad front. It then slowed and nearly stalled because of heavy Vietnamese resistance and difficulties within the Chinese supply system. On February 21, the advance resumed against Cao Bang in the far north and against the all-important regional hub of Lang Son. Chinese troops entered Cao Bang on February 27, but the city was not secured completely until March 2. Lang Son fell two days later. On March 5, the Chinese, saying Vietnam had been sufficiently chastised, announced that the campaign was over. The PLA withdrawal was completed on March 16.

Hanoi's post-incursion depiction of the border war was that Beijing had sustained a military setback if not an outright defeat. Nevertheless, the attack confirmed Hanoi's perception of China as a threat. The PAVN high command henceforth had to assume, for planning purposes, that the Chinese might come again and might not halt in the foothills but might drive on to Hanoi. By 1987 China had stationed nine armies (approximately 400,000 troops) in the Sino-Vietnamese border region, including one along the coast. It had also increased its landing craft fleet and was periodically staging amphibious landing exercises off Hainan Island, across from Vietnam, thereby demonstrating that a future attack might come from the sea.

Since the early 1980s, China has pursued what some observers have described as a semi-secret campaign against Vietnam that is more than a series of border incidents and less than a limited small-scale war. The Vietnamese call it a "multifaceted war of sabotage." Hanoi officials have described the assaults as comprising steady harassment by artillery fire, intrusions on land by infantry patrols, naval intrusions, and mine planting both at sea and in the riverways. Chinese clandestine activity (the "sabotage" aspect) for the most part was directed against the ethnic minorities of the border region (see Ethnic Groups and Languages , ch. 2). According to the Hanoi press, teams of Chinese agents systematically sabotaged mountain agricultural production centers as well as439 as lowland port, transportation, and communication facilities. Psychological warfare operations were an integral part of the campaign, as was what the Vietnamese called "economic warfare"--encouragement of Vietnamese villagers along the border to engage in smuggling, currency speculation, and hoarding of goods in short supply.

The Vietnamese have responded to the Chinese campaign by turning the districts along the China border into "iron fortresses" manned by well-equipped and well-trained paramilitary troops. In all, an estimated 600,000 troops were assigned to counter Chinese operations and to stand ready for another Chinese invasion. The precise dimensions of the frontier operations were difficult to determine, but its monetary cost to Vietnam was considerable.

Data as of December 1987