China’s nuclear-submarine mishap points to challenge of catching up with US

The reported sinking of a Chinese nuclear-powered submarine at a Wuhan shipyard highlights the difficulties Beijing faces in building an advanced oceangoing navy that can challenge U.S. maritime power.

China has been racing to expand its relatively modest fleet of nuclear submarines as part of a campaign to modernize its military and tilt the strategic balance with Washington in Beijing’s favor.

Building a potent nuclear submarine force would help China tighten control over its peripheral waters and shipping lanes, project power globally and improve its ability to seize the island democracy of Taiwan. The effort hit a snag this spring when, according to U.S. officials, China’s newest nuclear-powered attack submarine sank near the central city of Wuhan, The Wall Street Journal reported Thursday.

“Nuclear-powered submarine technology is one area where China has lagged, remains relatively weak and is trying to play catch-up,” said Nick Childs, senior fellow for naval forces and maritime security at the International Institute for Strategic Studies, a London-based think tank.

While the causes remain unclear, the mishap would at least “raise new questions about the design, quality control and training involved in China’s efforts to rapidly develop its submarine force,” Childs said.

Some analysts said that such accidents are par for the course in any effort to develop complex weapons systems, and the incident isn’t expected to deal lasting damage to China’s submarine program. The new vessel was salvaged but will take time to be rendered seaworthy.

“Any nation that is attempting what China is now doing is going to run into problems,” said Sam Roggeveen, a defense analyst at Lowy Institute, a Sydney-based think tank. “Even the most competent military forces will have accidents with submarines.”

The U.S. has suffered similar setbacks, such as the 1969 sinking of the nuclear-powered USS Guitarro at a California shipyard.

Chinese leader Xi Jinping has steered an ambitious modernization drive for the People’s Liberation Army over the past decade, comprising personnel shake-ups, organizational restructuring, arms procurement and technological research.

The goal is to forge a 21st-century fighting force that can match up with Western militaries—particularly at sea, where Chinese forces increasingly confront U.S. counterparts while asserting Beijing’s sovereignty claims over Taiwan and swaths of the South China Sea.

Xi’s military overhauls have run into teething problems over the years, including recurrent corruption scandals. Authorities have opened probes against more than a dozen senior generals and defense-industry executives over the past year or so, including on two former defense ministers who were expelled from the Communist Party in June.

The U.S. and other powers have boosted military spending and forged new coalitions to counter China’s growing military might. In 2021, the U.S., U.K. and Australia formed an alliance, known as Aukus, to help Canberra acquire nuclear subs and cement the West’s advantage in undersea military technology—a development that added urgency to Beijing’s quest for more capable submarines.

China boasts the world’s largest navy in terms of hull count, with more than 370 ships. While this numerical advantage is set to grow as Chinese shipbuilders continue cranking out warships, analysts say the PLA Navy remains some distance from matching its U.S. counterpart as a genuine oceangoing force that can project power well beyond coastal waters—in part because of Chinese deficiencies in undersea warfare.

China still relies heavily on diesel-powered submarines, which have shorter range and must surface much more frequently than nuclear-powered ones.

At the end of 2022, the Chinese navy’s submarine fleet featured 48 diesel-powered craft and 12 nuclear-powered units, including six attack subs and six ballistic-missile subs, according to a Pentagon report issued last year on China’s military power.

The U.S. submarine force, meanwhile, is entirely nuclear-powered and comprises 53 attack submarines, 14 ballistic-missile submarines and four guided-missile submarines.

“Nuclear-powered attack submarines are considered the apex predators of naval warfare,” said Roggeveen, the Lowy Institute researcher. China’s problem is that “they don’t have enough nuclear-powered submarines, and even the ones they do have are simply not of a high standard,” he said.

The U.S. Defense Department expects China to keep upgrading its submarine fleet by producing new diesel units to replace older ones and adding next-generation nuclear subs that can carry longer-range ballistic missiles. In its 2023 report, the Pentagon projected that China would operate 65 submarines by 2025 and 80 by 2035.

In terms of submarine warfare, China “fully recognizes that this is one area where they are lacking in,” and where “they feel the urge to close the gap as soon as possible,” said Collin Koh, a senior fellow and maritime-security specialist at the S. Rajaratnam School of International Studies in Singapore.

For China, mishaps in submarine development are “part and parcel of negotiating a very steep learning curve,” Koh said. “These accidents might even compel them to put more emphasis on the program.”

Write to Chun Han Wong at chunhan.wong@wsj.com