A UNITED STATES naval vessel passed through the South China Sea within 12 nautical miles of a Chinese artificial island on Thursday, in a move likely to agitate Beijing.
The Chinese military "immediately sent out warships" with two missile frigates identifying the United States naval destroyer and warning it away from Mischief Reef in the Spratly Islands, which China calls the Nansha Islands, according to China's foreign ministry.
He said Chinese Navy identified the USA warship, warned and expelled it.
USA national security advisor Lt Gen H R McMaster had said recently that "China is not doing enough on North Korea which continues to violate global norms by conducting missile tests".
They sought compliance with an arbitration ruling previous year that invalidated China's claims in the South China Sea.
China's foreign ministry said the operation had violated worldwide and Chinese law and seriously harmed Beijing's sovereignty and security.
The warship spat comes as a war of words between the USA and North Korea escalates and President Donald Trump pushes China to do more to reign in Pyongyang's threats.
Vietnam has competing claims over the Spratly Islands and was reportedly recently threatened by China to stop oil drilling.
In July, the USS Stethem, a guided-missile destroyer, sailed within 12 nautical miles of Triton Island in the South China Sea for the second "fonop".
Beijing said that a "joint effort" by China and other countries to address the territorial disputes has yielded "signs of positive developments".
The US says it supports none of the nations' claims in the area and insists that the sea should be a neutral space available for free navigation.
"They happen off the coast of Canada" and "in the waters off shore of our major allies, friends, partners all around the world", she said.
"The continuing reclamation and militarization of disputed territories in the waters, if the report from a Washington-based think tank are accurate, these can be taken up by the ASEAN in future discussions".
Missile systems and other defense infrastructure are believed to have also been installed on the islands, which the U.S. and China's neighbors fear could be used to project Chinese power into the area and potentially obstruct freedom of navigation.
But analysts feel the opening of the first Chinese military base overseas was in tune with PLAN's ambitions to expand its global reach amidst China's growing economic and political footprint.
The operation comes four days after the US, Australia, and Japan denounced China's island-building and militarisation of the South China Sea on the sidelines of a security forum of the 10-nation Association of Southeast Asian Nations (ASEAN) in the Philippine capital, Manila.
The archipelago is claimed in its entirety by China, Taiwan and Vietnam, while portions are claimed by Malaysia and the Philippines.