Chinese citizens lashed out online against billionaire Tesla and SpaceX CEO Elon Musk on Monday after China complained that its space station was forced to take evasive action to avoid collision with satellites launched by Musk’s Starlink programme.

The satellites from Starlink Internet Services, a division of Musk’s SpaceX aerospace company, had two “close encounters” with the Chinese space station on July 1 and Oct. 21, according to a document submitted by China earlier this month to the U.N.’s space agency.

“For safety reasons, the China Space Station implemented preventive collision avoidance control,” China said in a document published on the website of the United Nations Office for Outer Space Affairs.

The complaints have not been independently verified. SpaceX did not immediately respond to a request for comment.

In a post on China’s Twitter-like Weibo microblogging platform on Monday, one user said Starlink’s satellites were “just a pile of space junk,” while another described them as “American space warfare weapons.”

With nearly 30,000 satellites and other debris believed to be orbiting the planet, scientists have urged governments to share data to reduce the risk of catastrophic space collisions.

SpaceX alone has deployed nearly 1,900 satellites to serve its Starlink broadband network, and is planning more.

“The risks of Starlink are being gradually exposed, the whole human race will pay for their business activities,” a user posting under the name Chen Haiying said on Weibo.

U.S. space agency NASA was forced to abruptly call off a spacewalk at the end of November, citing risks posed by space debris. Musk tweeted in response that some Starlink satellite orbits had been adjusted to reduce the possibility of collisions.

China began constructing the space station in April with the launch of Tianhe, the largest of its three modules. The station is expected to be completed by the end of 2022 after four crewed missions.

Musk has become a well-known figure in China, though Tesla’s electric-vehicle business has come under growing scrutiny from regulators, especially after a customer climbed on top of a Tesla car at the Shanghai auto show in April to protest against poor customer service.