A Chinese coast guard fleet conducted a patrol near the Japanese-controlled Senkaku Islands in the East China Sea on Friday, the latest of more than two dozen forays into disputed waters this year at a time of high regional tensions over missile launches from North Korea.

The patrols came as Pyongyang has been firing ballistic missiles into the waters off the Korean Peninsula in the last two weeks. On Tuesday a missile launched over Japan prompted the U.S. to call an emergency meeting at the U.N. Security Council and to hold a trilateral ballistic missile defense exercise with allies Japan and South Korea.

The announcement came just over a week after three Chinese coast guard vessels spent more than eight hours in the waters off the disputed islands. The Japanese-controlled islands are also claimed by China, which calls them the Diaoyu Islands.

Chinese ships have been spotted entering the area that both countries call their own territorial waters 28 times this year.

Japan has yet to respond to the latest Chinese incursion, but in the previous incident on Sept. 28, Tokyo dispatched patrol vessels to chase off the Chinese ships and “lodged a stern protest with Beijing over the intrusion, which violated international law.”

Japan’s Deputy Chief Cabinet Secretary Yoshihiko Isozaki told reporters at that time that Beijing's action was "extremely regrettable and totally unacceptable.”

Changing status quo

Despite repeated protests from Tokyo, Chinese ships have been conducting regular patrols near the islands.

The same fleet led by a coast guard vessel 2301 carried out a similar patrol early June this year. 

The Japanese government bought most of the Senkakus from a private owner ten years ago. Since then, “China has been using this as an excuse to send the Coast Guard and other agencies’ ships into Japan’s contiguous zone almost every day except for stormy weather days, and these ships intrude into Japanese territorial waters several times a month,” said the Japanese Ministry of Foreign Affairs.

“This includes approaching Japanese fishing vessels inside Japanese territorial waters and intrusions by ships mounted with artillery,” it added.

Before the government’s purchase of Senkakus in 2012, Chinese ships almost never entered Japan’s territorial waters near the islands, according to the Japan Coast Guard.

The Senkaku Islands are a group of uninhabited islands in the East China Sea northeast of Taiwan that Japan has administered since 1895.

On Thursday, Japan, the U.S. and South Korea held a trilateral ballistic missile defense exercise in the waters between Korea and Japan, following North Korea’s ballistic missile launch over Japan on Oct. 4, according to a statement from the U.S. Indo-Pacific Command.

The three allies also staged a trilateral anti-submarine exercise for the first time in five years on Sept. 30.

Pyongyang has carried out six missile launches in less than two weeks as “countermeasures” to U.S.-led military drills in the region. 

The U.S. and South Korea responded with missile launches and drills around the Korean Peninsula on Tuesday and Wednesday, without Japan. (KB/RFA)