By Greg Torode

HONG KONG (Reuters) - A submarine arms race is intensifying as China embarks on production of a new generation of nuclear-armed submarines that for the first time are expected to pose a challenge to growing U.S. and allied efforts to track them.

Analysts and regional defence attaches say evidence is mounting that China is on track to have its Type 096 ballistic missile submarine operational before the end of the decade, with breakthroughs in its quietness aided in part by Russian technology.

Research discussed at a conference in May at the U.S. Naval War College and published in August by the college's China Maritime Studies Institute predicts the new vessels will be far harder to keep tabs on. That conclusion is credible, according to seven analysts and three Asia-based military attaches.

"The Type 096s are going to be a nightmare," said retired submariner and naval technical intelligence analyst Christopher Carlson, one of the researchers. "They are going to be very, very hard to detect."

The discreet effort to track China's nuclear-powered and -armed ballistic missile submarines, known as SSBNs, is one of the core drivers of increased deployments and contingency planning by the U.S. Navy and other militaries across the Indo-Pacific region. That drive is expected to intensify when Type 096s enter service.

The Chinese navy is routinely staging fully armed nuclear deterrence patrols with its older Type 094 boats out of Hainan Island in the South China Sea, the Pentagon said in November, much like patrols operated for years by the United States, Britain, Russia and France.

But the Type 094s, which carry China's most advanced submarine-launched JL-3 missile, are considered relatively noisy - a major handicap for military submarines.

The paper notes that the Type 096 submarine will compare to state-of-the-art Russian submarines in terms of stealth, sensors and weapons. It said that jump in capabilities would have "profound" implications for the U.S. and its Indo-Pacific allies.

Based partly on Chinese military journals, internal speeches by senior People's Liberation Army (PLA) officers and patent data, the paper charts more than 50 years of the PLA navy's often-glacial nuclear submarine development.

It contains satellite imagery taken in November at China's new Huludao shipyard showing pressure hull sections for a large submarine being worked up. That puts construction on schedule to have the boats operational by 2030, the timeline stated in the Pentagon's annual reports on China's military.

The research also details potential breakthroughs in specific areas, including pump-jet propulsion and internal quieting devices, based on "imitative innovation" of Russian technology.

Neither the Russian nor the Chinese defence ministries responded to Reuters' requests for comment.

The vessel is likely to be significantly larger than the Type 094, allowing it to contain an internal "raft" mounted on complex rubber supports to dampen engine noise and other sounds, similar to Russian designs.

Carlson told Reuters he did not believe China had obtained Russia's "crown jewels" - its very latest technology - but would be producing a submarine stealthy enough to compare to Moscow's Improved Akula boats.

"We have a hard time finding and tracking the Improved Akulas as it is," Carlson said.

Singapore-based defence scholar Collin Koh said the research opened a window on discreet research projects to improve China's SSBNs as well as boosting its anti-submarine warfare capabilities.

"They know they are behind the curve so they are trying to play catch-up in terms of quieting and propulsion," said Koh, of Singapore's S. Rajaratnam School of International Studies.

Carlson said he believed China's strategists would, like Russia, keep SSBNs within protective "bastions" close to its coasts, utilising recently fortified holdings in the disputed South China Sea.

ECHO OF THE COLD WAR

The prospect of advanced SSBNs will significantly complicate an already intense subsurface surveillance battle.

In an echo of the Cold War-era effort to hunt for Soviet "boomers", the tracking of Chinese submarines is increasingly an international effort, with the Japanese and Indian militaries assisting the United States, Australia and Britain, analysts and military attaches say.

Anti-submarine warfare drills are increasing, as are deployments of sub-hunting P-8 Poseidon aircraft around Southeast Asia and the Indian Ocean.

The United States, Japan, India, South Korea, Australia, Britain and New Zealand operate the advanced plane, which use sonobuoys and other more advanced techniques, such as scanning the ocean surface, to find submarines far below.

The United States is also carrying out the biggest overhaul of its top-secret undersea surveillance network since the 1950s to combat China's growing presence, Reuters reported in September.

The prospect of a quieter Chinese SSBN is driving, in part, the AUKUS deal among Australia, Britain and the U.S., which will see increased deployments of British and U.S. attack submarines to Western Australia. By the 2030s, Australia expects to launch its first nuclear-powered attack submarines with British technology.

"We are at a fascinating point here," said Alexander Neill, a Singapore-based defence analyst. "China is on track with a new generation of submarine ahead of the first AUKUS boats - even if they are at parity in terms of capability, that is highly significant," said Neill, an adjunct fellow at Hawaii's Pacific Forum think-tank.

Even if China's submarine force reaches technological parity, it will need to train aggressively and intensively over the next decade to match AUKUS capabilities, he added.

Vasily Kashin, a Moscow-based Chinese military scholar at HSE University, said it was possible Chinese engineers had made the breakthroughs described in the report.

Although China most likely obtained some key Russian technology in the 1990s after the break up of the Soviet Union, Kashin said, there was no known sharing agreement between Beijing and Moscow outside of a 2010 nuclear reactor agreement.

He said China may have made progress via adaptations of Russian designs and through other sources, including espionage, but it is unlikely they have the newest-generation Russian systems.

"China is not an adversary of Russia in the naval field," Kashin said. "It is not creating difficulties for us, it is creating problems for the U.S."

Analysis-Inside Asia's arms race: China near 'breakthroughs' with nuclear-armed submarines, report says