These may be the world's best warships. And they're not American

It's a growing problem that has United States naval commanders scratching their heads: How to keep up with China's ever-expanding fleet of warships.

Not only is China's navy already the world's largest, its numerical lead over the US is getting wider, with the head of the US Navy warning recently that American shipyards simply can't keep up. Some experts estimate China can build three warships in the time it takes the US to build one.

It is just one of the concerns, alongside Beijing's increasing aggression in the South China Sea and around Taiwan, that's likely to be weighing on the mind of US Defense Secretary Lloyd Austin as he joins top military figures from across the region at this weekend's Shangri-La Dialogue in Singapore.

The chance of a breakthrough on any of those issues this weekend appears slim, not least because China has pointedly rejected a US proposal for Austin to meet his Chinese counterpart Li Shangfu at the forum.

But experts who spoke to CNN before the summit say a potential solution to one of them - the Chinese fleet's numerical advantage - is within reach, if the US is prepared to think outside the box.

Washington, they say, has something Beijing doesn't: Allies in South Korea and Japan who are building some of the highest spec - and affordable - naval hardware on the oceans.

Buying ships from these countries, or even building US-designed vessels in their shipyards, could be a cost-effective way of closing the gap with China, they say.

Their warships are "certainly a match for their (Chinese) counterparts," says Blake Herzinger, a research fellow at the United States Studies Center in Australia, while Japan's warship designers "are among the world's best," says Carl Schuster, a former director of operations at the US Pacific Command's Joint Intelligence Center in Hawaii.

Both countries have mutual defense treaties with the US, so why doesn't the US team up with them to outbuild China?

The problem is, US law currently prevents its Navy from buying foreign-built ships - even from allies - or from building its own ships in foreign countries due to both security concerns and a desire to protect America's shipbuilding industry.

Schuster, Herzinger and others are among a growing body of experts who say it may be time to rethink that law to give the US an edge in the battle for the seas.

The Pentagon estimates China's navy to have around 340 warships at present, while the US has fewer than 300. It thinks the Chinese fleet will grow to 400 in the next two years, while the US fleet will take until 2045 to hit 350.

But it's not just the increasing vastness of the Chinese navy that has raised concerns. Some of the ships China is churning out arguably have greater firepower than some of their US counterparts.

Take China's Type 055, in many eyes the world's premier destroyer.

Displacing 12,000 to 13,000 tons, the Type 055 is bigger than typical destroyers (it is nearer in size to the US Navy's Ticonderoga class of cruisers) and packs a formidable punch.

It has 112 vertical launch system (VLS) cells that fire surface-to-air and anti-ship missiles, which is more than the 96 on the newest of the US Navy's Arleigh Burke-class destroyers. It also boasts sophisticated radio and anti-submarine weapons systems.

And China is pumping them out. It began building the Type 055s in 2014 and recently commissioned its eighth, the Xianyang. The US's work on its Zumwalt-class destroyers has been much slower; construction began five years earlier, yet only two have entered service.

But some Western analysts say the Type 055 may have a peer in South Korea's Sejong the Great-class destroyers.

At 10,000 to 12,000 tons displacement, the Sejongs are slightly smaller than China's Type 055s, but they have more firepower, with 128 VLS cells and weapons that include surface-to-air, anti-submarine and cruise missiles.

The three Sejongs, which cost about $925 million each, are the pride of the South Korean fleet.

"With this one ship, (the South Korean Navy) can cope with multiple simultaneous situations - anti-aircraft, anti-ship, anti-submarine, anti-surface - and defend from ballistic missiles," the country's Defense Media Agency says.

Retired South Korean Adm. Duk-ki Kim, the first person to captain a Sejong, says it's more than a match for China's Type 055.

"China is focusing on quantity and price competitiveness rather than the quality of its vessels," Kim, now vice president of the Korea Association of Military Studies, told CNN.

Japan, too, has "world class" destroyers, said Alessio Patalano, professor of war and strategy at King's College in London.

The country's newest Maya-class destroyers are armed with 96 VLS cells that can fire both anti-ballistic and anti-submarine missiles, while the "quality of its sensors and systems stands at the very top end of the spectrum," according to Patalano. Last November, the Mayas demonstrated their ability to destroy ballistic missiles traveling outside Earth's atmosphere.

Those 96 VLS cells put the Mayas on par with the newest of the US Arleigh Burkes, but there's a crucial difference between them: The Arleigh Burkes cost $2.2 billion; the Mayas cost a billion dollars less.

In other words, the Mayas represent both "quantity and quality": They are high-spec, (relatively) low cost and can roll off production lines at speed.

"If Chinese shipbuilding is showing a remarkable capacity for mass production, Japan's is leading the way in affordable quality on a scale larger than most naval powers, without sacrificing commissioning times. That balance, and the experience in the philosophy, are a genuine edge," Patalano said.

And it's not just the Mayas. Take Japan's Mogami-class frigates; speedy, stealthy 5,500-ton warships with 16 VLS cells that fire surface-to-air and anti-ship missiles. All done with a crew of 90 and a price tag of about $372 million each.

By contrast, the first of the US Navy's under development Constellation-class frigates are expected to cost three times as much and require twice as many crew. That's less than ideal given the US Navy is having a hard time recruiting - the US vice chief of naval operations has said it is likely to miss its recruiting goal by 6,000 this year - though the Constellations are expected to have twice as many VLS cells as the Mogamis.

Cost comparisons with China's Type 055s are harder due to the opacity of the Chinese system; estimates of their costs range anywhere from $925 million to $2.6 billion each.

So what's making South Korean and Japanese shipyards so competitive?

Cost overruns, endemic in US defense contracting, are not common in Japan, Schuster says, because - unlike the US - the country holds manufacturers to their estimates.

"A Japanese shipbuilder's bid is an absolute. If they finish it below expected cost, they make a larger profit. If they encounter delays and mistakes, the builder has to correct it at their own expense," Schuster said.

That approach was "much wiser" than that of the US, he claims, pointing to the alleged problems with Zumwalt-class destroyers and littoral combat ships that have seen the Pentagon spend billions on platforms that critics say the US Navy doesn't know what to do with.

The US Navy's three Zumwalt destroyers have priced out at about $8 billion each, but it's unclear how they fit into the rest of the fleet.

Meanwhile, some of the US's littoral combat ships, which cost more than $350 million each, are expected to be decommissioned before they have even served a third of their life span.

All these Japanese and South Korean vessels are designed to incorporate US technology, weapons, spy radars and the Aegis command and control system.

Partly this is so that the two navies can operate seamlessly alongside their US counterpart, as they did in joint exercises earlier this year.

But then if the US, Japanese and South Korean ships use similar technology and can operate together, why does the law prevent the US from building some of its ships in Japanese and South Korean shipyards?

The prohibition isn't just about security concerns. It's also aimed at keeping shipbuilding jobs and expertise within the US.

In 2019, total economic activity associated with the US shipbuilding industry accounted for nearly 400,000 jobs and contributed $42.4 billion in GDP, according to the Maritime Administration, with 154 shipyards spread across 29 states classified as active shipbuilders and more than 300 engaged in ship repairs or capable of building ships.

The US military is an important source of demand for these shipbuilders; while less than 3% of the vessels delivered in 2020 went to US government agencies, 14 of the 15 large deep-draft vessels went to a combination of the US Navy and the US Coast Guard.

Any move that might be perceived as threatening such an important industry would therefore be politically fraught. Shipbuilding representatives argue more needs to be spent on the domestic industry, rather than less, recently telling Congress the single biggest issue facing shipyards was attracting and retaining a quality workforce, according to USNI News.

US Navy spokesperson Travis Callaghan said, "The Navy currently has a significant number of ships under construction and on contract across several shipyards. We have also made and continue to make significant investments in our shipyards to increase and maximize capacity. The Navy is committed to providing a ready, modernized, and capable naval force that continues to be the nation's primary instrument of sea control both now and into the future."

There are also those analysts who, while admiring the shipbuilding prowess of Japan and South Korea, say getting them to build ships for the US would be a step too far.

Speaking on the sidelines of the Shangri-La Dialogue, Nick Childs, senior fellow for naval studies at the IISS, said US cooperation with its allies is already shifting the trajectory of naval power in Asia away from China.

There's "a new phase of maritime balance" in the region that has it slowly edging back in Washington's favor, Childs said. However, he doesn't think the answer is building US ships overseas.

"I think the answer is to learn from the way they do it rather than get them to do it for you," he said.

Still, proponents of outsourcing say employing the help of allies offers a more immediate fix - and point out the US already outsources designs overseas; its Constellation-class frigates are based on an Italian design and Japan has been mooted as a possible source for future blueprints.

But Schuster thinks designs aren't enough - the US needs more ships now, he says.

"Since shipyard availability is at a premium in the United States, having a portion of that work done in Japan would address that problem until America can refurbish and expand its shipyards - a 10-year process in most defense analysts' eyes," Schuster said.

Retired South Korean admiral Kim thinks partnering on shipbuilding offers everyone "a win-win."

Herzinger, too, thinks it's time to rethink the law.

Japan and South Korea "both build very high quality ships on time and on budget, both things (the US has) lost the ability to do," Herzinger said.

CNN's Haley Britzky, Gawon Bae, Jiwon Jeong and Moeri Karasawa contributed to this report.