Meanwhile, India's increased military investment after clashes with China on their disputed Himalayan border risks inflaming tensions with its longtime rival, Pakistan.

Similarly, countries with overlapping territorial claims in the South China Sea may struggle to maintain a diplomatic status quo as Beijing aggressively stakes its claim to strategically valuable shipping lanes.

The region is trapped in a "security dilemma" -- a geopolitical spiral where countries repeatedly reinforce their own militaries in response to the growth of their neighbors' forces, said Malcolm Davis, senior analyst at the Australian Strategic Policy Institute.

"The potential for a major power war is increasing," he said. "We are building up to a potential crisis."

The military rise of China

Under President Xi Jinping, China's military has rapidly expanded.

Along with the third aircraft carrier being built in Shanghai, the Pentagon claimed China recently tested a hypersonic missile.

And it isn't just China's military buildup that is unsettling the region, but its attitude as well.

"Such moves are extremely dangerous, just like playing with fire. Whoever plays with fire will get burnt," the statement quoted Xi as saying.

Arzan Tarapore, South Asia research scholar at Stanford University, said Beijing's aggressive posturing and diplomacy under Xi was alarming its neighbors. "This is not just the brashness of "wolf warrior" diplomacy but an apparent willingness to press its territorial claims with force," he said.

Since the end of World War II, the US has been a major guarantor of peace and stability in the region, particularly through its close security alliances with Japan, South Korea and the Philippines.

But the threat of a US withdrawal from the region under former US President Donald Trump, combined with his "America First" policies that saw the country turn inward, undermined trust in Washington's engagement in the region.

"I fear there will always now be a little asterisk when regional countries consider the US -- that it is not immune from domestic instability or strategic madness," Tarapore said.

Japan and South Korea build their forces

Two of the countries with the most rapid militarization are those geographically closest to China: Japan and South Korea.

There is no timeline for the unprecedented increase, but it would allow the Japanese government to quickly expand its forces at a time when Tokyo feels under growing pressure from neighboring North Korea and China.

While Japan's neighbor North Korea is often in the news for its missile program, South Korea is also rapidly expanding its forces. Seoul is looking to build up its military, partly to make it less reliant on its longtime security partner, the United States.

In September, Seoul announced it had successfully tested a submarine-launched ballistic missile (SLBM), one of the first major trials since Biden agreed to end a 40-year-old treaty limiting South Korea's weapons program.

While both Japan and South Korea are longtime US security partners, with uneasy relationships with China and North Korea, their bilateral ties are at times marred by historical grievances and territorial disputes.

The two governments regularly clash diplomatically over historic human rights abuses during the early 20th century, when Japan occupied South Korea, and experts said neither government is likely to want the other to pull ahead too far militarily.

"Some right-wing leaders in Tokyo will say, 'look at South Korea, it has an aircraft carrier, a full-fledged aircraft carrier, we need to have one also ... as a matter of national pride,'" Lionel Fatton, Indo-Pacific affairs expert at Webster University in Switzerland, said.

The slow arms race

Not every country allied with the US is seeking more military independence.

In a shock announcement in September, Australia tied itself more closely to Washington by forming a new security alliance with the US and UK in the Indo-Pacific.

Under the agreement, known as AUKUS, the allies will share information, including US technology that could see Australia acquire its own fleet of nuclear-powered submarines. That would allow Australia to extend its reach into the South China Sea while also solidifying a foothold for London and Washington in the region.

The decision made it clear that Australia was choosing the US over China, shifting the balance of the power in the Asia-Pacific.

It also unsettled nations across Southeast Asia, which are struggling to maintain a cordial relationship with Beijing while protecting their own interests.

But other claimants to the South China Sea -- including Philippines and Vietnam -- are struggling with their own military buildup, ASPI's Davis said.

Davis said the traditional stance for ASEAN nations, including Vietnam, Malaysia, the Philippines and Indonesia, has been to avoid conflict in favor of maintaining the status quo and remaining non-aligned.

But he warned any further aggression by Beijing in the South China Sea could push countries to adopt a more militaristic stance.

"If the Chinese declared an Air Defense Identification Zone in the South China Sea or took additional territories or started creating additional artificial islands ... (it) could actually then generate the ASEAN states to actually make that step," he said.

Military threats in South Asia

Apart from Taiwan, most experts said the most dangerous military standoff in Asia is the border between China and India.

But Stanford's Tarapore said the approach was still piecemeal. "The Air Force as a whole is in dire need of recapitalization, and the Navy is retiring submarines faster than it is replacing them," he said.

But any additional moves by India to beef up its armed forces may be viewed unfavorably by neighboring Pakistan, Tarapore said. The two nuclear powers have had an uneasy peace for decades, with multiple disputes across their land border.

Tarapore said it was unlikely India could tailor its military growth in a way which wouldn't cause concern in Pakistan -- and so it may not attempt to appease Islamabad and carry on regardless.

"Delhi knows that, short of some unlikely grand political bargain, the specific shape of its military modernization won't mollify Pakistan in any meaningful way, so it may as well do what's needed to meet its pressing military threats," he said.

A safer Asia Pacific?

China is showing no signs of halting its military growth, and Beijing has partially attributed that to one major factor -- the US.

In recent years, the American military has been growing its presence in the Asia Pacific region, including undertaking frequent Freedom of Navigation Operations near Chinese-held islands in the South China Sea and sailing vessels through the Taiwan Strait.

The Chinese Foreign Ministry has regularly accused Washington of being responsible for the militarization in the Asia Pacific. And as China builds up its forces in response, so too do the country's neighbors.

As a result, there is no end in sight for militarization in the region and most experts said it will likely speed up, increasing the chance for miscalculation and conflict.

Politicians and experts around the region have compared the arms race and tensions in the Asia Pacific to Europe in the 1930s, shortly before the start of World War II.

Peter Layton, visiting fellow at Griffith University's Asia Institute, said the chance of a war between major powers in the Asia region in the next 10 years is rising, but he hopes economic and trade interdependence between China and its rivals in Asia, as well as the US, could help to deter any military action.

"The question is whether the economic system is strong enough to avoid military conflict," he said. However Layton said while the economic interdependency might prevent war in Asia, it could spark growing economic coercion across the region, such as the trade restrictions China has leveled at Australia over the past year.

"They can ... use positive or negative sanctions to control most people using the power of money," he said.

ASPI's Davis said while he expects the arms race in Asia to make the region more dangerous, he doesn't think nations have "much of a choice."

He believes the Chinese government's aggressive behavior and military modernization will continue no matter how its neighbors react. "Even if we didn't respond, they would keep on going," he said.

In fact, Tarapore said it is possible that military weakness in and of itself could provoke aggression, while military power "may also be frightening to erstwhile aggressors and serve to deter rather than provoke war."

The time is coming, Tarapore said, when countries in Asia will have to choose "what form of safety is most important to us" -- the safety of a military deterrent or any protection offered by acquiescing to Beijing's expansion.

"Arms races are costly. Losing them can be costlier," he said.