China’s new nuclear sub sinks at shipyard — suggesting Beijing is in over its head

China lost its most advanced nuclear submarine when it sank in a naval yard earlier this year — and it suggests the Communist nation could be in too deep as tries to build a navy to rival America’s maritime might.

The Chinese Zhou-class, the first of a new class of nuclear-powered attack subs, went down at a shipyard near Wuhan in late May or early June, the Wall Street Journal reports.

The Chinese military has kept quiet about the incident while touting it’s “maritime superiority” in the South China Sea — with eyes on a possible invasion of Taiwan.

Nuclear submarines are capable of running longer and at higher speeds than conventional subs, which China already operates. Attack submarines like the Zhou-class are designed to quietly stalk and attack enemy ships, including US aircraft carrier groups — and slip away without detection.

The Zhou would represent a new, more dangerous capability for China’s People’s Liberation Army Navy.

The submarine sub was likely part of China’s new fleet that was outlined in a Pentagon report last year on China’s military might.

The asserted that China is developing new subs, naval ships and aircraft carriers to counter the US and its allies in the event of an invasion of Taiwan — the self-ruled, democratic Chinese island that Beijing claims is a breakaway province.

Retired Rear Adm. Mark Montgomery, a Foundation for Defending Democracies senior fellow, told The Post that the submarine’s failure would represent “a real setback for China because the first ship in class basically sets the track for the ships to follow.”

“Delays caused by repairing this ship will hinder follow on submarine production,” he said.

Montgomery added that such a production issue is not unheard of; US and Soviet subs sank while docked in the 1960s and 1970s.

“This incident may be a sign of moving too fast, that the PLA-Navy is working hard to catch up to US nuclear submarine capabilities,” said the former commander of America’s carrier strike group in Japan.

The incident was first flagged in July by Thomas Shugart, a former US submarine officer and fellow at the Center for a New American Security, who noted strange actions occurring at the Wuchang Shipyard.

Shugart viewed commercial satellite images depicting a new submarine stationed at the shipyard, with the arrival of floating cranes suggesting something had gone amiss.

The sub, built by the government’s China State Shipbuilding Corp., was floating in the Yangtze River in late May before the cranes arrived, according to the satellite photos.

It remains unclear why the submarine sank, if there were any casualties and whether it was carrying nuclear fuel at the time.

American officials told the WSJ that there were no signs that Chinese officials have been testing the nearby water for radiation.