The Japan Coast Guard said Monday it has finished deploying 12 ships assigned exclusively to patrolling areas around the Senkaku Islands amid China’s growing assertiveness in the East China Sea.

The 10 new 1,500-ton patrol ships and two helicopter-equipped patrol vessels will become fully operational this month as part of efforts to strengthen protection of waters off the uninhabited islets that are claimed by both China and Taiwan.

After tensions heightened with China following the Japanese government’s purchase of most of the islands from a private Japanese owner in September 2012, the Coast Guard’s 11th regional headquarters, which is based in Okinawa and oversees the area, has received help from other regions to patrol the Senkakus.

The regional HQ will no longer need outside help thanks to the new ships, while other regional units will be able to focus again on their normal duties, such as responding to maritime accidents, in their own areas, the Coast Guard said.

The 10 new ships, equipped with 20-mm guns and water cannons, are 96 meters long and capable of high-speed pursuits. The other two were transferred from other regional units and have been overhauled.

Besides the 12 new ships, the Okinawa division has six 1,000-ton or larger patrol ships and one helicopter-equipped patrol vessel, which will engage in operations other than those related to the Senkakus.

Piers and lodging facilities are being prepared at Ishigaki port in Okinawa so it can serve as a base for the patrol ships. The fixed number of personnel for the 11th regional division has been increased to 1,722, of whom 606 are assigned exclusively to Senkakus patrol activities.

Japan has seen a sharp rise of intrusions by Chinese vessels in its territorial waters around the islands after the 2012 purchase. The number of such ships at one point exceeded 20 per month, but it has dropped to less than 10 recently.

Tensions still remain, however. Late last year, China Coast Guard vessels, including one apparently armed with guns, were spotted sailing in Japanese territorial waters near the disputed islands.

On Monday, three China Coast Guard vessels were found sailing near the islands. They entered a contiguous zone just outside Japanese territorial waters, according to the Japan Coast Guard, making it the ninth straight day that Chinese government vessels had been spotted near the Senkakus.

“We will continue to deal with the situation firmly and in a level-headed manner under the policy of decisively protecting our territorial waters,” Japan Coast Guard Commandant Yuji Sato said earlier.