With China plowing money into its military machine and making aggressive claims to disputed island chains, Beijing's regional rivals are investing in the one weapon that can undercut the increasingly potent People's Liberation Army.
Across South and East Asia, China's neighbors are spending heavily on submarines, purchasing silent diesel-electric machines capable of slipping past Chinese defenses.
So when the Australian reported this week that detailed technical plans — totaling some 20,000 pages — for a French-made submarine had leaked from the manufacturer, the reaction was one of widespread panic. The leaked plans outlined in minute detail the capabilities of a Scorpene-class vessel purchased by India, and New Delhi immediately demanded that French authorities investigate how the respected DCNS shipbuilder had lost control of the plans.
In Australia, where DCNS has been tapped to build the country's next-generation submarine, officials warned the contractor needed to step up security.
The sharp reaction reveals the central place of submarines in Asia's accelerating arms race. Submarines are one of the few weapons with which countries warily eyeing Beijing's military buildup can send a signal that they do not plan to stand idly by as China asserts its interests through coercion and unilateral moves, particularly in the South China Sea. Australia, Vietnam, Malaysia, Indonesia, Japan, and India can do little about the formidable radar installations and missile batteries dotting China's coastline, as well as its expanding fleet of naval ships and warplanes, but they can build vessels capable of slipping underneath Beijing's naval cordon.
That's because while China has spent billions of dollars upgrading many aspects of its armed forces, from fighter jets to naval destroyers, its ability to carry out anti-submarine warfare still lags behind, said Bryan Clark, a senior fellow at the Center for Strategic and Budgetary Assessments. And that has left a tactical opening for China's rivals.
"These countries are really seeing these submarines as the capital ships of their navies," said Clark, a former U.S. Navy submariner and advisor to the service's top brass.
What was for much of the 20th century a mere commerce raider, in other words, is now becoming a way to project power. Jonathan Greenert, the former chief of naval operations — the top job in the U.S. Navy — said submarines are an attractive weapon for countries in the Asia-Pacific, and governments in the region will likely ratchet up their spending on the vessels amid growing concern over China's missile arsenal.
"You can deliver destructive power in a stealthy manner, and that's a deterrent. We see more of that taking place," Greenert said.
That's why this week's news of an apparent leak of classified operating data of advanced submarines is so worrisome to countries like India and Australia, both of which have committed to buy advanced submarines from DCNS, the French shipbuilder. The leak revealed crucial information, such as diving times, torpedo ranges, and above all noise profiles while operating underwater.
Emmanuel Gaudez, a spokesman for DCNS, said the leaks are a "serious matter" that are being "investigated by the proper French national authorities for defense security," who "will determine the exact nature of the leaked documents, the potential damages to DCNS customers, as well as the responsibilities for this leakage."
The submarine race comes as China is denying adversaries access to its coastal waters through an expanding array of missiles and naval bases. Powerful radars light up American, Japanese, and other ships that patrol the Western Pacific. Cutting-edge satellites peer down from space to mark them for potential targeting. And Beijing has deployed scores of missile batteries capable of hitting targets hundreds of miles away all along the coast.
In response, Vietnam, which has repeatedly clashed with China over rival territorial claims in the South China Sea, has bought six Russian-made Kilo-class submarines worth $2.6 billion since 2009 for deployment at Cam Ranh Bay. The Kilo-class diesel-electric subs — able to operate nearly silently and armed with shorter-range torpedoes and sea-skimming anti-ship missiles with a range of 188 miles — would force China to think twice before entering into a confrontation with Vietnam. Hanoi also is looking at acquiring U.S.-made P-3 Orion anti-submarine patrol aircraft to track China's subs.
Although China has a vast naval fleet — including 70 submarines — that far outnumbers Vietnam's navy, Beijing might be hard-pressed to track Hanoi's newly acquired subs, which can move with stealth and strike like an undersea guerrilla force. Hanoi's submarine fleet offers a form of asymmetric warfare against a much stronger opponent, in keeping with Vietnam's strategic tradition honed on land during its successful wars against the United States and France.
Vietnam's sub purchase is part of a steady rise in military spending across Asia. Over the past decade, countries across the region have built up advanced militaries, led by China's huge jump in arms spending. Asian arms spending rose 5.4 percent from 2014 to 2015 — compared with 1 percent worldwide, according to the Stockholm International Peace Research Institute.
Indonesia is also in the market for stealthy diesel subs and is anxious to expand its small fleet from two vessels to seven. It announced plans last year to purchase two Russian-made Kilo-class submarines and is awaiting the delivery of three South Korean-built subs ordered in 2012. Jakarta reportedly plans to deploy some of the vessels — along with fighter jets — to a base in the Natuna Islands, an area that overlaps with China's expansive territorial claims in the South China Sea.
India has looked on with alarm as China has begun to operate submarines in the Indian Ocean in recent years, and the government has committed to an ambitious plan to build 24 submarines over the next 30 years in a bid to keep up with Beijing's undersea prowess.
But the Scorpene submarine project has been plagued by delays and is already several years behind schedule. The first submarine in the class was supposed to be delivered in 2012, but the INS Kalvari, the first of six planned Scorpene vessels, only entered sea trials this year.
With the Scorpene project already lagging behind, the leak of thousands of pages of sensitive data about the submarine dismayed Indian officials. And the secret spilling also shook Australia, where the government has awarded a controversial $38 billion contract to DCNS to build a cutting-edge submarine. Based on a design for France's own new nuclear submarine, the so-called Shortfin Barracuda would provide Canberra with the ability to project power across the vast swaths of ocean to Australia's north.
The Shortfin Barracuda is a scaled-down version of France's flagship submarine that has swapped nuclear propulsion for diesel-electric. It is a highly capable submarine that can carry out long missions at sea and is equipped with an American combat control system.
"It'll be the best diesel submarine in the world if they achieve it," Clark said.
Paris lobbied hard to win the lucrative contract for DCNS — over Washington's objections. The White House pushed Australia to award the contract to Tokyo in a bid to strengthen Japan's defense industrial base at a time when the United States is seeking to have its key East Asian ally shoulder greater responsibility for countering Chinese military moves in the region.
The breach at DCNS of highly sensitive information about the Scorpene sub has raised questions about the company's information security and whether it can keep the technical specifications of the vessel secret in the face of intense interest in Beijing about its capabilities. The data breach will be at the top of the agenda when India's defense minister, Manohar Parrikar, holds talks on Monday at the Pentagon with U.S. Defense Secretary Ash Carter.
The potential fallout from the leak could extend to other countries that have also ordered versions of the Scorpene vessel, including Chile, Malaysia, and Brazil.
But it remains unclear how much of the Scorpene leak is actually available in the public domain. Cameron Stewart, the associate editor for the Australian who broke the news of the leak from DCNS, reported that the information may have been taken from the shipbuilder by a former French Navy officer working as a subcontractor.
"I don't believe that the information was stolen for the purposes of espionage but rather for the purpose of assisting as reference material for a military course with a navy in Southeast Asia," Stewart told Foreign Policy. "But then the original holder of the data lost control of it to another company, and that company then held the data. What they did with it, or if they knew it was valuable, is unclear."
"It had spent at least several years in Southeast Asia by that stage after being removed from France in 2011," Stewart said. "I am confident that the data was not leaked beyond its recipient in Australia, but it remains unknown if the data was copied, intercepted, or otherwise compromised while it was in Southeast Asia."
But with a long list of countries looking to make submarine purchases, officials at DCNS are also examining whether or not the leaks could have been an act of corporate espionage.
"We don't know if economic warfare is the point of the start of the leaks against the company," Gaudez, the spokesman, said. DCNS is currently competing for submarine contracts from Norway and Poland, and the company will surely face questions following the leak of information about whether it can keep sensitive technical information secret.
"Competition is getting tougher and tougher, and it might be a tool which might be used," Gaudez said.