China’s defence ministry has demanded an end to US military operations in the South China Sea, saying they pose a threat to regional security and increase the risks of collisions and even nuclear leaks in the strategic waterway.

Ministry spokesman Tan Kefei also repeated China’s demand for an explanation of what happened to a US nuclear attack submarine which collided with a mystery object in the disputed waters earlier this month, describing Washington’s statement – issued six days after the incident – as “short and unclear”.

“This irresponsible and covert approach lacks transparency, and can easily lead to misunderstanding and misjudgment. China and the neighbouring countries in the South China Sea have to question the truth of the incident and the intentions of the United States,” he said on Tuesday.

According to the US Navy, the USS Connecticut – a Seawolf class SSN – collided with an unknown object in the South China Sea on October 2, injuring 11 sailors on board. The report said the submarine’s nuclear propulsion system was not affected and it was able to return to the Guam naval base for follow-up checks.

No further details were provided, including the extent of the damage, what kind of object the sub had collided with, or the specific location of the accident.

The US Navy report said an assessment and preliminary repairs to the damaged sub were under way and two investigations would also be undertaken. Chinese state media, think tanks and officials have questioned whether there was a nuclear leak.

Tan said the incident showed the US was posing a serious threat to the region through its freedom of navigation operations in the South China Sea.

China regards the operations as an infringement of its maritime sovereignty, while the US says they are necessary to counter China’s advancing military build-up in the disputed waters.

“Under the banner of ‘freedom of navigation and overflight’ the US military frequently dispatched advanced weapon platforms such as aircraft carriers, strategic bombers and nuclear submarines to show off force and stir up trouble in the South China Sea, seriously threatening regional national security and exacerbating regional tensions. This is also the source of this collision,” Tan said.

He added that US actions had made all countries in the region uneasy.
“The United States should stop approaching reconnaissance in the sea and airspace adjacent to China’s South China Sea and reefs and its military deployment against China, and stop conducting so-called freedom of navigation operations in the South China Sea,” he said.

Tan also said the Aukus deal – under which the US and Britain will provide Australia with nuclear submarines – would further intensify the risks facing the region.

The deal “will trigger an arms race in the region and damage the non-proliferation framework in Southeast Asia. The risk of nuclear leak will increase and this will bring severe challenges to regional peace and security,” he said.