Three Chinese coast guard vessels sailed around the Diaoyu Islands in the East China Sea on Monday, the country's maritime authorities have revealed, days after U.S. Defense Secretary James Mattis vowed to defend Tokyo's control of the islands.
China's State Oceanic Administration did not give further details on the patrol, the latest salvo in a China-Japan dispute over the islands' sovereignty.
The Japan Coast Guard confirmed that the Chinese ships had started cruising around the uninhabited islands at around 2 p.m. on Monday and left about two hours later.
China's foreign and defense ministries have so far made no comment on the incident.
Mattis, U.S. President Donald Trump's new defense secretary, said in Tokyo last week that the island chain was subject to a longstanding Washington-Tokyo defense treaty that the new U.S. administration would honor.
In a statement on Sunday, Chinese Foreign Ministry spokesman Lu Kang responded, "Diaoyu and its affiliated islands have been Chinese territory since ancient times. These are historical facts that cannot be changed. The so-called U.S.-Japan security treaty was a product of the Cold War, and it should not harm China's territorial sovereignty and legitimate rights."
"We urge the U.S. side to adopt a responsible attitude and stop making wrong remarks on the issue of the sovereignty of Diaoyu Islands," Lu said. | 
