China’s naval buildup now includes a new class of attack submarine that employs both conventional and nuclear propulsion, according to defense officials.

The new Zhou-class submarine was confirmed by the Pentagon last week after one of the boats was seen in satellite images partially submerged beside the pier as the result of an unknown mishap.

Defense analysts at the Pentagon assess the new Zhou-class attack submarine that sank near Wuhan is “a new class of nuclear submarine that is similar in size to [People’s Liberation Army] navy conventionally powered submarines, but with a small nuclear reactor,” a U.S. defense official said, speaking on background.

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The official said it was unclear if the shipyard near Wuhan that built the submarine is certified to handle nuclear materials.

“As such, we do not know if the submarine reactor was fueled at the time of incident, or if it is going to be relocated to a known nuclear-certified facility for its initial fueling, such as Huludao shipyard, which has built all previous PLA] navy nuclear submarine classes,” the official said.

China’s military and government have been silent on the incident, a possible sign that reports about the mishap are accurate and that Beijing wants to hide the incident.

“It’s not surprising that the PLA Navy would try to conceal the fact that their new first-in-class nuclear-powered attack submarine sank pier side,” a senior defense official said. “In addition to the obvious questions about training standards and equipment quality, the incident raises deeper questions about the PLA’s internal accountability and oversight of China’s defense industry — which has long been plagued by corruption.”

Some U.S. intelligence officials have questioned whether China’s large-scale military buildup of both nuclear weapons and conventional arms is producing an effective fighting force.

However, China recently conducted a test of a long-range ballistic missile that for the first time in more than 40 years traveled far enough to fall in the Pacific Ocean. A photo of the launch published in Chinese state media revealed the missile as a DF-31 intercontinental ballistic missile.

Spotting the sub

The damaged submarine, which the Pentagon identified as a Type 041 SSN, was first spotted by former Navy submariner Tom Shugart, a defense analyst with the Center for a New American Security who reviewed satellite imagery of the Wuchang shipyard near Wuhan that showed unusual crane barges around the pier where the submarine was seen partially submerged. The images from May or June suggested that the cranes were moved into position in an effort to recover the damaged craft.

It is not the first time that China has managed to build a new class of submarine in secret.

The Washington Times first disclosed on July 16, 2004, that China had developed a new Yuan-class conventionally powered submarine in secret.

The first submarine was unknown to U.S. intelligence until it was spotted at a pier near Wuhan – just like the new Zhou-class attack submarine.

Discovery of the new submarine was a “technical surprise” for the U.S. intelligence community, which had no previous knowledge of the vessel, a defense official acknowledged. A satellite image taken March 10 by Maxar Technologies revealed that the Zhou-class submarine prior to sinking was designed with an X-shape tail end.

Mr. Shugart said on X that the nuclear-propulsion system for the Zhou, if confirmed, would mark “a significant expansion of nuclear submarine production outside of Huludao.”

Unconfirmed reports that China was using auxiliary nuclear power plants for electricity generation for conventional submarines have circulated for years, he said.

A combined conventional-nuclear system for submarines is not a surprise, Mr. Shugart noted.

Other defense analysts have challenged the Pentagon reporting on the new submarine by noting the difficulties of moving submarines from Wuhan, on the relatively shallow Yangtze River, to deeper waters.

However, analysis of the imagery shows the new submarine is around 10% longer than earlier attack submarines and is smaller and easier to move than larger missile submarines.

Mr. Shugart told The Washington Times that the sinking of the submarine is a short-term setback, but that “I don’t see it significantly altering the overall trajectory of improvements in PLA Navy capability.”

“We lost a submarine at the pier in 1969, and that didn’t keep us from winning the Cold War competition at sea,” he said.

Other key takeaways are that the incident reveals China appears to have a second nuclear submarine shipyard, and that the new sub will be able to deploy dual, towed sonar arrays that suggest it is a major upgrade from the Yuan-class submarines also produced near Wuhan, he said.

Going nuclear

Rick Fisher, a China military affairs analyst, said retired PLA Rear Adm. Zhao Dengping in 2017 revealed plans for a small nuclear auxiliary engine for conventional submarines, along with other advanced naval warfare developments.

The plans for the nuclear-conventional hybrid sub were disclosed on Chinese military websites, said Mr. Fisher, an analyst with the International Assessment and Strategy Center.

“Adm. Zhao described a new unidentified 7,000-ton nuclear-powered attack submarine (SSN) that will feature a ‘new type of power plant, …new weapon system [and] electronic information system,’” Mr. Fisher stated in a recent article posted on the website of the Center for International Maritime Security.

The system was described by the admiral as a novel low power/low pressure auxiliary nuclear power plant for electricity generation that would fit into conventional submarine designs. The system could be a replacement for the current Stirling engine-based air independent propulsion (AIP) systems, he said.

The slides indicated that the PLA navy plans to continue building smaller submarines modified with the new nuclear auxiliary power that will provide greater endurance at sea.  

The nuclear power plant appears similar to the Soviet-Russian designed VAU-6 auxiliary nuclear power plant tested in the late 1980s on a Project 651 Juliet conventional cruise missile submarine, Mr. Fisher said.

Gen. Zhao’s disclosures are “a very rare revelation, in perhaps unprecedented detail, of a portion of the PLA’s future modernization ambitions,” Mr. Fisher said.

The Pentagon’s most recent annual report on the Chinese military states that the PLA has placed a high priority on modernizing its submarine force, which “grew modestly” with advanced technology and expanded shipyards.

China currently operates six nuclear-powered ballistic missile submarines and six nuclear-powered attack submarines, along with 48 diesel electric boats.

The overall submarine force is expected to increase to a total of 65 submarines by 2025 and 80 submarines by 2035.