China said on Wednesday that U.S. high altitude balloons flew over its Xinjiang and Tibet regions, and it will take measures against U.S. entities that undermine Chinese sovereignty as a diplomatic dispute festered.

China said earlier this week that U.S. balloons had flown over its airspace since May 2022, without giving details. Foreign ministry spokesman Wang Wenbin has said U.S. balloons made round-the-world flights. “Without the approval of relevant Chinese authorities, it has illegally flown at least 10 times over China’s territorial airspace, including over Xinjiang, Tibet and other provinces,” Wang said on Wednesday. The White House has disputed China’s allegations.