The U.S. Navy's harbor security team works with the Japanese coast guard in Sasebo harbor in this undated photo. The Japanese coast guard plans to deploy more patrol boats to ports in the country’s southernmost island chain to counter increasing Chinese incursions into its territorial waters. (Courtesy of the U.S. Navy)

CAMP FOSTER, Okinawa — The Japanese coast guard plans to deploy additional patrol boats to ports in the country’s southernmost island chain in the coming months to counter increasing Chinese incursions into its territorial waters.

The strategy calls for a unit of small patrol vessels to be placed on a still undetermined island in the Yaeyama chain along with six 1,000-ton large patrol vessels on Ishigaki, the largest of the Yaeyama Islands, accompanied by port upgrades that will facilitate the move, spokesman Shinya Terada said Wednesday. Yaeyama is about 90 miles east of northern Taiwan.

The move would increase the number of coast guard patrol vessels and small crafts in the southern region from 33 to 42 by March, the end of the Japanese fiscal year.

“In response to the continuous intrusion of Chinese government vessels, Japan will take a firm stance to protect our territorial waters,” Terada said. “The large patrol boats are in response to Chinese government vessels, while the small patrol boats are in response to Chinese fishing boats.”

The move comes at a time of increased tension between the onetime foes. China has disputed Japan’s rights to the resource-rich Senkaku Islands, northwest of Yaeyama, and Chinese officials have been cited in state-run media disputing Japanese sovereignty over Okinawa.

Chinese officials have refused to let Japan off the hook for its World War II aggression, while modernizing their military and aggressively expanding territorial claims throughout the region in disputes with several countries.

Terada did not say how the coast guard would respond if it spots Chinese vessels. China has clashed in recent years with coast guard officials and fishermen from Vietnam, South Korea and the Philippines when caught in similar situations.

The U.S. has signed security and mutual defense agreements with Japan that require its support during military conflict. Stepping up coastal patrols would not contribute to clashes, Terada said.

The number of incursions into Japanese territorial waters has skyrocketed in recent years, Terada said. Chinese government vessels have been intruding into Japan’s territorial waters about five times per month since ownership of the four Senkaku Islands was transferred to Japan from private citizens in September 2012, according to the coast guard.

In 2012, 39 Chinese fishing boats intruded into Japanese waters surrounding the Senkakus. That number jumped to 208 vessels in 2014. In December 2012, a Chinese aircraft intruded into Japanese airspace over the Senkakus, a Ministry of Foreign Affairs spokesperson said.

Japan’s Ministry of Defense declined to comment on the situation, saying maritime security is the coast guard’s jurisdiction.

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