There are no U.S. surveillance aircraft in Chinese airspace, White House national security spokesman John Kirby said on Monday, repeating denials of China’s claim that U.S. high-altitude balloons had flown over its airspace without permission more than 10 times since the beginning of 2022.

Asked at a White House press briefing to clarify whether the United States was operating aircraft in Chinese-claimed airspace as opposed to over China’s internationally recognized territory, Kirby declined to specify further.

“There is no U.S. surveillance aircraft in Chinese airspace,” he said.

China says the self-governed island of Taiwan is its territory. It also claims vast swathes of the South China Sea, to which other countries, including Brunei, the Philippines, Malaysia and Vietnam, also lay claim.

Washington supports a 2016 ruling under the UN Convention on the Law of the Sea (UNCLOS) that invalidated most of China’s claims to maritime rights in the South China Sea. The U.S. military at times conducts what it calls freedom of navigation operations in disputed waters near atolls where Beijing has built up military bases.

Those operations anger Beijing, which accuses the United States of damaging regional stability and stirring up controversy over maritime disputes.

China’s accusation about balloons widened a dispute with the United States that began after the U.S. military shot down on Feb. 4 what it says was a Chinese spy balloon, whose appearance prompted top U.S. diplomat Antony Blinken to cancel a trip to Beijing that had been designed to ease tensions.

Since then, the U.S. military has shot down three other objects over North America, most recently on Sunday, when an octagonal object was downed over Lake Huron, the Pentagon said.