THE REAGAN administration, which has committed more than its share of blunders in the Middle East, may finally be doing something right in the Persian Gulf.

The American naval armada in the gulf seems to be succeeding in its limited mission of protecting convoys of reflagged Kuwaiti tankers. The Saudis and other gulf Arabs would like us to do more and extend protection to all non-belligerent shipping; others at home and abroad would like us to do less -- which means the Reagan administration probably has struck the balance about right.

What's needed now is to combine our military success in the gulf with a new diplomatic push to end the Iran-Iraq war. That trick -- translating military muscle into diplomatic gains -- hasn't been the Reagan administration's strong suit. But administration officials say they are pushing this month for a vote on a United Nations resolution aimed at forcing Iran into peace talks.

The U.S. armada can't stay in the gulf forever, and at some point, the administration should probably adopt the late Sen. George Aiken's strategy for ending the Vietnam War: Declare victory and get out. We haven't reached that point yet. But the administration is sensibly beginning to reduce the number of ships in and around the gulf. The number of U.S. warships there on Friday was 24, down from last October's peak of 34, according to a Defense Department spokesman. Though the Pentagon won't yet confirm it, administration officials say the battleship Iowa and the helicopter carrier Okinawa will be leaving the area soon.

The quiet -- and in many ways boring -- success of the gulf task force contrasts with the dire predictions that greeted its initial deployment. When the administration decided nearly a year ago to send a small armada to the Persian Gulf to escort Kuwaiti tankers, many politicians and pundits saw a disaster in the making.

The tanker-reflagging plan was a "half-baked, poorly developed" scheme and an attempt to "show our macho," said Senate Democratic leader Robert C. Byrd. "I don't think anyone knows quite what the policy is," worried Senate Republican leader Robert J. Dole.

Even the Central Intelligence Agency had the jitters. Amid the congressional hand-wringing over reflagging, the agency prepared an intelligence estimate warning that Iran was likely to retaliate against the American naval force with a new wave of terrorism. Sources say the CIA was so skittish about maintaining its analytical independence that when Frank Carlucci, then national security adviser, asked to see a draft of the estimate, he was told that he would have to wait until it was finished.

The Iranian terror campaign feared by the CIA hasn't yet materialized. The agency's analysts have offered several hypotheses for Iran's behavior, sources say. Among the theories: The Iranian terror network may be less extensive than the CIA thought; improved American and European intelligence and security measures may have cramped their operations; the threat of American retaliation may have deterred them from attacking; or they may still be looking for the right target.

The best explanation for Iran's restraint may simply be that they know how to count ships. Attacking American targets when we have massive firepower in the gulf just isn't worth the risk. As one administration official observes: "The events of the past year have shown that the Iranians have no interest in a large-scale, open confrontation with the United States." The best measure of the administration's success in the gulf is to look back to the situation that existed a year ago. It was a mess: Iranian troops were pounding the Iraqi city of Basra, and Iraqi morale looked shaky; the Reagan administration was reeling from the Iran-contra affair and its credibility in the Arab world was near zero; the Soviet Union was offering military protection to the gulf Arabs, as an alternative to the seemingly unreliable Americans.

The Reagan administration responded to this chaotic situation by agreeing last March to a request from the tiny sheikdom of Kuwait to reflag Kuwaiti tankers and provide American naval protection for them. It seemed at the time (and still does) like a strange way to respond to the larger problem of the Iran-Iraq war. But as one administration official explains: "We felt we needed to do something tangible to show support for our friends in the gulf, and we grabbed the first opportunity that came along."

The tanker-escort policy got off to a bad start. In May, the USS Stark was hit by an Iraqi missile, killing 37 American sailors. When the first convoy of reflagged tankers finally moved through the Strait of Hormuz in July, one of them, the Bridgeton, promptly struck an Iranian mine. Minesweepers eventually arrived but the impression persisted for months that the gulf operation was snakebit.

Since that maiden voyage last July, 32 U.S.-escorted convoys have made their way safely through the gulf. Meanwhile, the Pentagon has developed innovative tactics to deal with most aspects of the Iranian threat. To maintain radar coverage of Iran's flotilla of small speedboats, the United States has converted at least two oil-drilling barges into offshore bases for Army helicopters; to allow prompt retaliation against future Iranian attacks, the Navy has programmed its Tomahawk cruise missiles to hit a range of Iranian targets.

The American response to the Iranian Silkworm missile attack on the Sea Isle City last October was typical of the gulf policy as a whole. In retaliation, U.S. helicopters destroyed an Iranian speedboat base at the Rostam oil platform in the gulf. It was what the bureaucrats call a "measured response" -- a political-military amalgam that sought to frighten the Iranians, without frightening the U.S. Congress even more. Like the larger policy, it was halfway between doing nothing and going to war against Iran.

The Iranians, being rational, have responded to the American naval presence in the obvious way. Recognizing that if they attack American-flag ships they will get clobbered, the Iranians instead wait for them to steam off the horizon -- and then attack unprotected ships that aren't flying the American flag. That galls some of our Navy captains, and the Saudis (whose ships are still being attacked in large numbers) have been working very hard to make America feel guilty about it.

We shouldn't. Despite the presence of our armada in the gulf and our encouraging military successes, this isn't America's war. The goal of American policy in the gulf is to stop the Iran-Iraq war, not to get deeper into it.

David Ignatius, an associate editor of The Washington Post, edits the Outlook section.