South Korea on Thursday began a two-day regular exercise near two islets it controls in the Sea of Japan that are also claimed by Japan, the South’s navy said.

The South Korean military conducts exercises around the rocky outcroppings, known as Takeshima in Japan and Dokdo in South Korea, roughly twice a year. The navy said the latest exercise also involves the air force, but provided few details.

The exercise until Friday was expected to involve five to six vessels and four to five aircraft, according to Yonhap News Agency.

A similar drill was last held in June with six warships and seven aircraft, drawing a diplomatic protest from Japan, which views the islets as its own.

The two islets and small reefs around them have a combined area of 0.21 square kilometer and are situated roughly equidistant from the Korean Peninsula and Japan’s main island Honshu.

South Korea took effective control of the islets in 1954, when it dispatched a permanent battalion there.

==Kyodo