INDIA AND PAKISTAN regularly offer parallel reassurances that they can handle their newly enhanced nuclear status as well as -- better than -- the traditional nuclear powers handle their own. They tend to take their friends' expressions of anxiety about their nuclear maturity as offensive and having some ulterior or gratuitous purpose. But as the latest sequence on their border in divided and disputed Kashmir indicates, the South Asian pair have themselves a way to go before international concerns are likely to be substantially eased.

The immediate facts of the Kashmir incident are, typically, in dispute. India saw the hand of the Pakistani government in an infiltration of hundreds of armed Muslims across the 450-mile "line of control" separating Pakistan-held Kashmir from India-held Kashmir. Pakistan saw a "very very serious" provocation in the Indian airstrikes that followed. It was India's first use of air power in peacetime; the two have warred three times, twice over Kashmir. It was also the largest military exchange since a proud India and, shortly thereafter, a responding Pakistan conducted nuclear tests just a year ago. Nor is the current episode yet played out: Later in the week Pakistan claimed it had downed two Indian warplanes over its territory.

In turning to (conventional) arms as they have, however, the two sides neglected the tried and true rules of coexistence between two hostile nuclear powers: Don't shoot, keep the rhetoric cool and treat grievances with heavy doses of diplomacy. The United States and the Soviet Union came by these sensible guidelines in their decades of experience in the Cold War. They followed these rules to the fruitful result that no shots were ever directly exchanged between these two extravagantly armed powers. Having learned, notably, in the Cuban missile crisis of 1962, they understood the requirement for restraint in word as well as deed, lest something get started that might eventually escalate to a nuclear level.

Yet here are India and Pakistan flexing their power in a raw border clash as though their respective tests had never altered the nuclear equation holding between them. Pakistan continues irresponsibly to stoke insurgents in the part of Kashmir it does not control. India continues to deny self-determination to the people of Kashmir, choosing instead to pursue a policy of hegemony in the Asian subcontinent.

On the evidence of the latest trouble, neither party has thought through its new obligations for acting in ways, in diplomacy and in military affairs as well, that lead away from nuclear confrontation, not toward it. Their wars and the wasted periods between them were always painfully costly to the two of them. Another war now could widen the zone of danger. Both India and Pakistan are new at the nuclear game.