With victory in the bag, some of the allies in the Persian Gulf war seem to feel less and less pressure to help the United States foot the bill.

Understandably, this expectable but regrettable tendency bothers the Senate Appropriations Committee, which has been holding hearings on an emergency appropriation to cover the costs of the war.Some parts of the Defense Department already have spent most of their appropriations for fiscal 1991. So swift congressional action is needed on the request for $15 billion from American taxpayers to set up a "working capital" account that would cover war costs until more contributions come in from our allies.

But the measure is still no substitute for the persistent arm-twisting that seems to be needed if various allies are to make good on their promises.

So far, the United States has received only $14.9 billion of the $53.5 billion it was promised by allies around the world. Even the $53.5 billion may not be enough to cover the costs of the war, which the Pentagon estimates could run as high as $77 billion.

The worst case of foot-dragging involves Japan. Not until last week, until the shooting was all but over, did the Japanese parliament formally approve a pledge of $9 billion that had been committed earlier. No funds have reached Washington so far. Yet Japan, which is almost wholly dependent on imported oil, is a major beneficiary of the war to expel Iraq from Kuwait.

Even Saudi Arabia, which was on the verge of being annexed by Iraq before U.S. troops intervened, has paid only $6 billion of the $16.8 billion it promised.

Other allies with big unpaid commitments include Germany, the United Arab Emirates, South Korea and Kuwait.

Unhappily, some of the nations behind in their payments are those with the greatest ability to foot the bill. If these nations don't start paying up, the United States may have little choice except to start applying pressure in the form of trade embargoes and tariffs.