On Monday and Tuesday, four Chinese coast guard ships sailed near the Diaoyutai Islands, one of which was equipped with a cannon, reports Taipei Times.

Two of the ships sailed away on Tuesday morning, including an armed vessel, while the others attempted to approach a Japanese fishing boat, the Japan Coast Guard said, reports the news portal.

The uninhabited islands located on the East China Sea, are claimed by Taipei, Beijing and Tokyo.

It was the first armed incursion since China’s enactment on Feb. 1 of a new Coast Guard Law, which authorizes its coast guard to inspect and use weapons on foreign vessels in waters claimed by Beijing, Taipei Times.