The United States flew two B-1B Lancer bombers over contested regions of the South China Sea on Friday as part of an effort to assert that the waterway remains international territory despite China’s claims of sovereignty.

China has laid claims over nearly the entirety of the South China Sea, despite overlapping claims from a number of other nations in the region and the United States’ position that the international waters are not subject to China’s rule.  China has rapidly expanded its military presence in the region in recent years, launching as many as 18 new naval vessels since the beginning of 2016, and developing a number of artificial islands they are currently equipping with military personnel and hardware.

China responded to Friday’s flight by accusing the United States of parading its military might in the region under the guise of freedom of navigation.

Chinese Foreign Ministry spokesman Geng Shuang explained to the media that China has no problem with freedom of navigation or overflights of the South and East China Seas, “But China resolutely opposes individual countries using the banner of freedom of navigation and overflight to flaunt military force and harm China’s sovereignty and security,” he said.