Many naval officers termed it the ultimate embarrassment: U.S. warships trying to avoid underwater mines by cowering behind the massive reflagged Kuwaiti supertanker they had been sent to protect in the troubled Persian Gulf.

The scene -- three Navy ships plowing single-file behind the mine-crippled Bridgeton -- was symbolic of the poor planning, inadequate capabilities and politics that have plagued U.S. mine-sweeping forces, according to Navy, Pentagon and congressional leaders.

While billions of dollars have gone into state-of-the-art aircraft carriers, missiles and bombers in recent years, the threat to ships from relatively low-technology, low-cost mines claimed a low priority in U.S. military thinking. And when the Reagan administration attempted to pump more money into the ailing program, poor management, cost overruns and design faults left improvements years behind schedule.

The Navy has come under intense scrutiny for its mine-countermeasures program and its failure to provide adequate protection for dangerous escort missions through the Persian Gulf in the aftermath of the explosion that ripped a 22-foot hole in the hull of the reflagged Bridgeton on July 24, the second day of a U.S.-sponsored convoy.

A banner headline in The Times of London last week said, "U.S. Navy Incompetence Dramatized by Mine Foul-Up."

"The Navy knows it has egg all over its face, and it's extremely embarrassed," said one congressional source who monitors military programs.

While the Navy's escort ships bristle with sophisticated weapons to combat air and sea attacks, the Navy had taken no precautions against the old, reliable tactics of mine warfare. Pentagon officials say they did not expect to encounter underwater explosives so far out in the gulf's shipping channels.

"One has to ask how it was the channel wasn't swept," former Navy secretary John F. Lehman Jr. said in an interview. "I don't know the answer."

But Navy underwater teams, after laborious searches with Kuwaiti and Saudi mine sweepers, have found a number of old-fashioned contact mines moored just beneath the surface of gulf channels used by deep-draft supertankers such as the Bridgeton, which draws 66 feet fully loaded.

So far, the searchers have not encountered more sophisticated mines, which lie on the bottom and are detonated by the sound of a ship's propeller, its magnetic field or pressure from its hull through the water.

Pentagon officials concede that U.S. mine-hunting and sweeping capabilities are extremely limited. The force includes 21 aging wooden ships, only three of which have active duty crews; a handful of small COOPS (Crafts of Opportunity, which frequently include boats seized in drug raids); 23 Sea Stallion helicopters, and a few smaller choppers that can be outfitted for mine-hunting.

Lehman and others note that the United States traditionally has depended on allies with greater mine-sweeping capabilities to supplement the small U.S. force. But the tensions of the gulf, torn by almost seven years of war between Iran and Iraq, highlight the problems with the policy, officials note. Many U.S. allies are hesitant to antagonize Iran by aiding escorts of ships from Kuwait, a supporter of Iraq. Britain and other allies have turned down belated U.S. requests for mine-sweeping help.

The Reagan administration in the early 1980s launched a $1.5 billion program to build a new class of ocean-going ships to replace the mine-sweeper fleet, 1950s-vintage wooden ships suffering from dry rot and leaks. There were to be 14 large Avenger mine sweepers, and 17 small, high-technology fiberglass boats for coastal patrols.

The first Avenger arrives this fall -- two years late and much costlier than estimated. Among other problems, the engines and main gears built for the first two Avengers did not match. The main gears were incorrectly designed to rotate in directions opposite those of engine shafts on the ships.

Congress complained bitterly when the price of two ships jumped from an original $197.2 million to $256.6 million. This year, angered by delays, Congress refused to provide money for three more ships.

The coastal sweeper program ran into trouble when design flaws caused the hull to split open during simulated mine explosions. With costs soaring, the Navy scuttled the effort and instead will buy an Italian-built coastal vessel. An informed congressional source called the program "a disaster."

Lehman, who oversaw much of the program, said: "Of all the programs in shipbuilding we've wrestled with, the programs that absorbed more effort with less effect were those mine-sweeping programs."

Lehman blamed "poor management in the production yards and the Navy asking for too much technology to begin with."

Meanwhile, there are big problems with the service's ambitious helicopter mine-sweeping program, which calls for building a new version of the Sea Stallion that was ordered to the Persian Gulf this week. The RH53E Super Stallion has serious safety problems, and Congress, while generally supportive, has not approved the helicopters requested for 1989.

The Senate noted this year that it has "learned about serious deliberations within the Navy over the safety of the RH53. The Navy's chief safety officer recommended a top-down review of the structural dynamics . . . noting that bandaid fixes have failed to resolve the structural safety issue." The Navy also ordered a 15-month test program to try to resolve the safety problems.

The gulf's harsh environment -- searing heat, high water temperatures and dust clouds that billow out from the land -- creates additional hardships for the crews and equipment tediously hunting and sweeping for mines.

More time is required to maintain vessels and machinery, a problem that will face the Sea Stallion helicopter mine hunters as well. Desert sands and high temperatures were a major factor in the failures of another version of that helicopter during the unsuccess- ful attempt in 1980 to rescue

the U.S. Embassy hostages in Iran.

Mine-sweeping is extremely time-consuming and requires overlapping search paths, "just like mowing a lawn," said one naval mine expert.

Although mine-sweeping helicopters are faster and more versatile than ships, the heavy sleds and sweeps they tow from long, heavy cables require so much time to set up that the Sea Stallion's normal 3 1/2-hour flying time is sharply curtailed.

Assistant Navy Secretary Everett Pyatt said last week that the Navy is at least five years away from catching up on its schedule for putting new mine sweepers into the fleet.

Meanwhile, some military experts, including retired admiral Wesley L. McDonald, former deputy chief of naval operations, say the United States may not be able to continue relying so heavily on its allies. McDonald estimates that the number of allied mine-sweeping ships, 600 vessels in 1968, will shrink to about 200 by 1990.

Others have predicted an increase in mine threats.

"We should expect more terrorism like the mines to be directed at our strategic interests around the world in the years ahead," Scott Truver, a maritime policy analyst, told participants of a mine warfare seminar sponsored by the Naval Institute in Annapolis in 1985.