Anti-mine ship USS Defender trails 1,800 feet of 'mag-tail' cable Nov. 7, 2009, through which it will run 250 volts of electricity to create a magnetic field to detonate magnetic mines in the Pacific Ocean near Japan on Nov. 7, 2009.

A generation ago, the Navy vowed to get better at finding and destroying sea mines.

The proclamation came months after the first Gulf War, when Iraq’s use of more than 1,000 underwater bombs overwhelmed the Navy’s fleet of anti-mine ships and helicopters. Two U.S. warships were rocked by explosions, and the Pentagon was forced to abort plans for an amphibious assault on Kuwait, leaving some 30,000 Marines stuck at sea.

More than 20 years after that embarrassment, the sea service is still working to make good on its promise to fully address a centuries-old threat that some analysts have called the Navy’s Achilles’ heel.

“Only when things go bad and ships can’t go where they need to go do we seem to care about mine countermeasures,” said Scott Truver, a Washington-based defense analyst who has spent 30 years studying mine warfare. “It’s easier to sell a new nuclear submarine program or a new aircraft carrier.”

Today, after hundreds of millions of dollars in research and development — and despite some meaningful gains in technology — the Navy’s core mine countermeasures force looks a lot like the one that struggled two decades ago in the Persian Gulf.

The service relies primarily on 11 Cold War-era mine countermeasures ships and a dwindling fleet of heavy-lift helicopters to sweep and clear underwater minefields. Plans to retire the Navy’s Avenger-class ships and its 28 remaining MH-53E Sea Dragon helicopters have been delayed over the past decade.

The aging ship and helicopter fleets have struggled with maintenance issues in recent years, but both will be needed for at least another decade. That’s because the Navy’s new minehunting technology is still being developed — delayed along with the troubled littoral combat ship that is intended to play a major role in future countermine operations.

The Navy says its new fleet of littoral combat ships will be fully operational and ready to clear mines by 2019. But a report this week by the Government Accountability Office found the Navy hasn’t yet demonstrated that its new anti-mine systems will be able to handle the job.

Some analysts worry the new systems won’t be ready before the old ones need to be shut down.

A spate of Sea Dragon accidents since 2012 — including a deadly crash off the coast of Virginia Beach in January — spurred the Navy to devote more attention to its oldest and most crash-prone helicopters. And the service’s fleet of Avenger-class ships shrank by 20 percent over the past year after the Navy retired two and had to scrap another that ran aground near the Philippines.

“The mines are getting more sophisticated,” Truver said. “The systems we put in place 20 years ago are wearing out. They have been ridden hard and put away wet. We’re now trying, in a period of deep budgetary restraints, to transition to a new way of doing mine countermeasures.”

Mines are cheap and easy to produce. They’re also extremely dangerous and difficult to detect. Of the 19 Navy ships seriously damaged or sunk since World War II, 14 were done in by mines.

After the first Gulf War, the Navy consolidated its mine warfare force under a single command based in Texas. But after a 2005 restructuring, the Navy changed course. There is no longer a centralized command or admiral solely devoted to mine countermeasures, a mission that also’s carried out by explosive ordnance disposal units and a team of mine-hunting dolphins.

“It’s fragmented,” said Paul Ryan, a retired rear admiral who served from 2000 to 2004 as head of the Navy’s Mine Warfare Command, which has since been merged with the San Diego-based anti-submarine warfare command. “There is no single champion for mine warfare.”

The Navy’s investment in its anti-mine force has traditionally followed a cyclical pattern, said Bob O’Donnell, a retired captain who directed the service’s program office for mine warfare in the years following the first Gulf War.

“We start out with low funding for mine countermeasures,” O’Donnell said. “Then mines cause a problem. The Navy rushes funds into mine countermeasures. The mine threat is diminished. Interest in mine countermeasures wanes. Money dries up. And then repeat.”

After focusing elsewhere for much of the past decade, O’Donnell said, the Navy has renewed its interest and investment in mine warfare, spurred in part by Iran’s 2012 threat to lay mines in the Strait of Hormuz. About of fifth of the world’s oil supply moves through the congested chokepoint; shutting it down for even a day would likely cause oil prices to soar.

That same year, separate reviews revealed problems with the Navy’s existing and future countermine forces.

A third of the Navy’s remaining Sea Dragons weren’t even equipped to sweep for mines, and only a single Avenger-class ship was able to conduct its required anti-mine missions at any given time.

In a report that July, the director of the Navy’s operational test and evaluation force found that the littoral combat ship’s, or LCS, core systems for identifying mines — a sonar sled and an advanced laser designed to detect mines from a helicopter — were “deficient” for their primary task. It was the latest in a series of setbacks for the LCS program.

Since then, the Navy has spent more than $300 million to boost existing mine countermeasures forces, including upgrades to aging equipment. Every Sea Dragon is now equipped for minesweeping, and most of the Avenger-class ships have received significant engine and sonar upgrades.

Adm. Jonathan Greenert, the chief of naval operations, has earned a reputation as a high-ranking advocate for the niche mine warfare community. He acknowledged weaknesses in the Navy’s dedicated mine countermeasures force after becoming the service’s top officer in 2011 and has committed resources to fix it.

Under his watch, the Navy has invested in what it terms a “transition force” for mine countermeasures: underwater and surface robots that should help bridge the gap between old and new platforms, said Capt. Glenn Allen, the head of the Navy’s mine warfare program office.

“I’m not concerned with there being a capability gap” between the existing and future mine countermeasures force, Allen said. “It’s correct that many of the LCS programs were behind deadline, but since that time, the program has done a great job to bring it back, and I believe we’re on target now.”

Allen agrees that the Navy has historically ignored mine countermeasures in favor of more prominent, offensive weapons systems. Even within the small anti-mine community, mine warfare is jokingly referred to as the Navy’s stepchild. This time, Allen said, he believes the Navy has finally committed for the long haul.

“I’ve been involved in mine warfare for 25 years, and you do tend to get a chip on your shoulder,” Allen said. “It is a community that does more with less. It is amazing what our sailors can do with a small number of resources.”

The future of mine warfare will be rooted in drastic advancements in technology, Allen said. Some of those improvements have been 25 years in the making. The LCS relies heavily on unmanned vehicles to clear mines, a change designed to remove sailors from the minefield.

But the Navy has yet to prove it has corrected problems with its new mine hunting sonar and laser detection system, according to the GAO report published this week. The report was also critical of a change in tactics that will require three separate searches before a mine is destroyed: One device is deployed from a ship to locate underwater objects that might be mines. A second device is deployed to scan those objects to determine if they are in fact mines. And a third device is deployed to disarm the mines.

That approach will slow the process, the GAO report said. And O’Donnell, the former mine warfare boss, said the strategy might reduce effectiveness. The upgraded Avenger-class ships are able to find, identify and disarm a mine without ever losing contact with it. Sea Dragons can pull a sled through the sea that cuts the cables to a certain depth of any moored mines, a one-step process that clears the way for more intensive mine hunting.

Nothing planned for the LCS replaces that capability.

“With the future system, after you find a possible mine, you have to re-acquire that contact twice,” O’Donnell said. “What happens if you’re not able to locate it the second or the third time? Can you confidently say you’ve cleared the minefield if that happens?”

The Navy argues that using the LCS for anti-mine missions will allow it to respond more quickly, cover more territory and keep sailors out of harm’s way. Its future mine-clearing force will have three times the capability of the current force, a Navy official told a Congressional subcommittee last summer.

Other challenges remain. The Navy had planned to buy 52 littoral combat ships; in late February, Secretary of Defense Chuck Hagel announced that the Pentagon would purchase only 32. Allen said the reduction shouldn’t affect the anti-mine program.

No amount of money can fully eliminate the threat of mines, analysts say. Sea mines are increasingly regarded as a likely weapon for terrorist groups and rogue nations looking to disrupt global commerce.

More than a quarter-million sea mines are held in the inventories of 50 navies around the world — including Iran, China and North Korea — and they come in more than 300 varieties, the Navy estimates. That figures doesn’t include underwater improvised explosive devices, which can be fashioned from fuel bladders, 50-gallon drums and even discarded refrigerators.

“We’ve been vulnerable to the threat for years,” Truver said. “We will never be able to buy enough ships and mission packages to declare all major waterways are clear. We’re never going to be able to have enough assets.”