China's southern border remains uneasy and Peking may be preparing some threatening military maneuvers but foreign observers here have so far failed to detect any concrete signs of China moving toward a new invasion of Vietnam. "We don't see as yet any buildup in concrete terms," said one experienced diplomat. "The Chinese do have military exercises in the south every fall, and they might just decide to conduct ever bigger exercises to worry the Vietnamese.

Observers here say the Chinese appear concerned about continued Vietnamese belligerence in the border area. They appear to want to discourage in some way an expected Vietnamese offensive against remnants of the pro-Chinese Pol Pot forces in Cambodia when the dry season returns in December.

But diplomats with access to several sources of information on the border situation discount reports of a Chinese buildup. They do not foresee China repeating anytime soon its punitive strike against Vietnam of February and March.

The diplomats here attribute reports of a buildup to a steady stream of accusations by the Vietnamese not sufficiently backed up by hard information. Before the February invasion, the enormous increase in soldiers and military equipment in southern China was evident even to casual travelers. Diplomats here say they expect the Chinese would commit even more resources to ensure the success of a second strike against a better-prepared Vietnam. A group of American journalists touring refugees camps in southern China two weeks ago saw no signs of major buildup.

"The Vietnamese will probably continue to press on the border and in Cambodia, and the Chinese may reach a point where they fell they have to stop talking and do something," he said.

Foreign diplomats advance many of the same reasons for avoiding a second-strike that they did before the first invasion. Fighting the Vietnamese requires heavy expenditures that drain money from China's limping economy and also risks Soviet intervention on China's northern border.

There also have been unconfirmed reports circulating here of serious disagreement within the Chinese leadership over the wisdom of the February invasion, which cost several thousand Chinese lives and failed to quell Hanoi's efforts to wip out China's friends in Cambodia.

Some Chinese leaders and foreign analysts apparently argue, however, that the invasion did force Hanoi to move some troops from the Cambodian area to the Chinese border, gave Chinese diplomatic threats new credibility and provided a useful test of the readiness of a Chinese Army that has not has a major war in 25 years.

"China's logic may not be our logic," warned one diplomat who had predicted the first strike against Vietnam would not occur.

Some observers here suggest the Chinese may choose simply to build up some border forces -- or conduct large maneuvers in the south to pressure the Vietnamese without actually incurring the costs of a new invasion. But a diplomat said he had seen "nothing that would indicate unambiguously that the Chinese are rebuilding. The movements I have seen have only indicated ordinary troop rotation and some defensive work."

Foreigners who have talked to Chinese officials about the situation think Peking appreciates the resilience of the Vietnamese and Hanoi's ability to accept years of economic hardship and military costs such as it is now undergoing following its invasion of famine-striken Cambodia.

"The Chinese do not believe the Vietnamese are at the end of their tether," one diplomat said.

The Chinese appear to have no great admiration for the Pol Pot forces whom they see as undercutting their own rule in Phnom Penh by harsh measures against their people. Yet Peking apparently plans to continue to support as the "only standing force there against the Vietnamese" while looking to support other anti-Vietnamese rebels in Cambodia who might surface.

In the meantime, China's own regular talks with Vietname have made no progress and seem to be continuing only as a convenient device in case some reconciliation becomes possible in the unforeseen future.