An American warship sailed near a disputed island in South China Sea on Sunday in an attempt to challenge the separate ownership claims by China, Taiwan and Vietnam, The Guardian reported.

The USS Stethem intentionally came within 12 nautical miles of Triton Island, which is part of the Paracel Island chain in the South China Sea, a U.S. Defense Department official told the news outlet.

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Twelve nautical miles is an internationally recognized marker of distance for another foreign country's territorial limits.

The operation that had a guided-missile destroyer sail within those 12 miles was meant to send a signal that the U.S. does not recognize any of the three nations' territorial claims of the island. Fox News first reported the operation on Sunday.

“Unlike in the Spratlys, where China has created new artificial territory in the last several years, it has effectively controlled the Paracels since 1974,” Mira Rapp-Hooper, a South China Sea expert at the Center for a New American Security, told the Guardian.

Despite largely praising Chinese President Xi Jinping, President Trump has also mounted pressure on Beijing to do more to sway North Korea to halt its nuclear programs and attempted missile launches.

The Trump administration last week fined two Chinese citizens and a shipping company for their efforts in helping North Korea’s nuclear and missile programs.

Trump is set to speak with Xi and Japanese Prime Minister Shinzo Abe on Sunday, before he formally meets both of them outside of the Group of 20 summit in Germany next week.