IF CHINA INTENDED to teach the Vietnamese a sharp lesson, either for Hanoi's contribution to their border dispute or for its invasion of Cambodia, then it must be disappointed.For the Vietnamese border militia -- not even the main force -- appears to have put up a very good show. And notwithstanding the attack, Hanoi went ahead on schedule a day later to formalize its patronage of the Cambodian regime it had just set up in Phnom Penh.

The Chinese have shown that they are prepared to resist by arms the consolidation of what they take to be a Soviet-dominated Vietnam's control of Indochina. But they have not intimidated Vietnam. They now face a question familiar to Americans in their time: whether to go on, with uncertain result, or to stop and devise a good way to get out. Dare one ask if this is China's Vietnam?

The Kremlin initially warned Peking "to stop before it is too late" -- a formulation suggesting that it was not yet "too late." This still seems to underlie Soviet restraint. Things could change if Moscow determines that its Vietnamese ally is in serious distress. And no matter how the war develops, a closer tie between Moscow and Hanoi seems likely, perhaps in the form of Soviet base rights at Camranh Bay. But a widening of the war, by a Soviet move against China, does not seem in the cards.

The Carter administration still hopes to luck it out: to see the war steered into the United Nations, and to avoid having the relationship with either Moscow or Peking impaired. With SALT on its mind, Washington wants Moscow to appreciate its efforts to talk the Chinese out of attacking and, now, to urge Peking to cease fire and withdraw. It wants Peking to know that the attack has not affected normalization, that it is urging Moscow to stay cool, and that it has linked its objection to China's "border penetration" with its objection to Vietnam's "invasion" of Cambodia. The Russians, suspicious as ever, claim that the American attitude favors Peking, and so it may in this round. What vitiates the Russian complaint is that Moscow's friends in Hanoi, by overrunning Cambodia, opened and won the last round. The United States alone has opposed both incursions.

It is a relief, though hardly a matter for self-congratulation, that the United States has no military part in this war.It is a conflict brought on by local rivalries, and by Sino-Soviet rivalry, in a region where Americans have scant taste even for diplomacy, and scant influence. Yet this country cannot ignore hostilities that always hold the prospect of expanding, and which affect its separate relations with the parties.

Specifically, the administration, by going along with the normalization schedule that China devised to fit its own geopolitical designs, cast a certain impression in Moscow that the United States supported Peking's plans. No doubt the Russians are doing their best to inflate American anxieties on this score. But to see the new China connection complicating dealings with Moscow at a moment when the SALT negotiations are nearing a climax is troubling all the same, the more so since the Chinese have broadcast wide their view that the whole SALT process is a snare.

We do not allege that great or lasting harm will come of this. We do suggest that the administration, for all its eagerness to gain advantage in its new relationship with China, cannot afford to ignore China's interest in exploiting its new relationship with the United States for purposes that Americans do not share. Taiwan is not the only matter raising questions between Washington and Peking.