China’s People’s Liberation Army Air Force has announced that it will be organizing “regular” exercises that fly past the so-called first island chain — a key entryway into the western Pacific that includes Japan’s Ryukyu Islands and Taiwan.

In the latest exercise, air force spokesman Shen Jinke said China had sent a fleet of aircraft that included H-6K bombers, Su-30 fighters and air tankers over the Bashi Strait and into the western Pacific for a “routine” combat simulation drill Monday, state media reported.

The fleet conducted reconnaissance and early warning training, sea surface cruising and in-flight refueling, and achieved all the drill’s targets, the official Xinhua News Agency reported.

“This is common practice for the air forces of sea-adjacent states, and a normal requirement for China’s national defense and military-building,” Shen said, adding that the move was “in accordance with international law and practice.”

The Xinhua report also said the air force would focus on improving the quality of such drills, “flying over island chains, controlling the East China Sea and cruising the South China Sea.”

China and Japan are involved in a territorial disputed over the Senkaku Islands in the East China Sea. Japanese and Chinese coast guard vessels frequently face off around the Japanese-controlled islands, known as the Diaoyus in China, as both sides press their claims.

Beijing is also embroiled in a dispute with several other claimants over the South China Sea.

In July, an arbitration court in The Hague ruled that China did not have historic rights to those waters and criticized its environmental destruction there. China rejected the ruling, calling it “waste paper,” and has vowed to ignore the decision.

Beijing claims most of the South China Sea, through which more than $5 trillion of trade moves annually. Brunei, Malaysia, the Philippines, Taiwan and Vietnam have rival claims.

Experts say the extensive chains of Pacific islands that ring China are seen by some in Beijing as a barrier designed during World War II by the United States that can contain China and its navy. Still other Chinese military theorists reportedly view the island chains more as benchmarks or springboards for Chinese military operations.

Japan has reportedly responded to China’s growing forays past the first island chain by stringing a line of anti-ship and anti-aircraft missile batteries along 200 islands in the East China Sea stretching 1,400 km from the country’s mainland toward Taiwan.

“For some … the island chains have become markers in China’s attempts to develop a ‘blue water’ navy capable of performing both wartime and peacetime missions,” wrote Andrew S. Erickson, of the China Maritime Studies Institute at the Naval War College, and Joel Wuthnow, a research fellow with the Center for the Study of Chinese Military Affairs at the U.S. National Defense University, in a February post to the National Interest website.