The Self-Defense Forces and the U.S. military on Thursday began a large-scale joint exercise mainly in and around Japan's southwestern islands, in an effort to boost their operational capability in those areas, with China's intensifying military moves in mind.

The exercise, called Keen Sword, is scheduled to last until Nov. 19 and will involve around 26,000 personnel from the Japanese ground, maritime and air self-defense forces and about 10,000 U.S. soldiers, including those from the Space Force, according to the Defense Ministry.

Drills simulating the defense of remote islands will be focused on Tokunoshima Island in Kagoshima Prefecture, with Japanese and U.S. Osprey tilt-rotor aircraft deployed there, the ministry said.

A total of four warships and two airplanes from Australia, Canada and Britain will also join the drills, which are in principle held every two years. From Japan and the United States, some 20 and 10 vessels and about 250 and 120 aircraft will take part, respectively, according to the ministry.

The ministry said the exercises are aimed at strengthening the deterrence and response capabilities of the SDF and U.S. forces in dealing with contingencies, as they oppose any unilateral attempts to alter the status quo by force.

Tokyo and Washington have been increasingly concerned about Beijing's maritime assertiveness in the Indo-Pacific region, including Chinese vessels' repeated intrusions into Japanese territorial waters near the Senkaku Islands.

The Japan-controlled, uninhabited islands in the East China Sea are also claimed by China, which calls them Diaoyu.

China has also intensified military activities near Taiwan, a self-ruled democratic island which the communist country regards as a breakaway province to be reunified with the mainland, by force if necessary.

Exercises will also involve responding to ballistic missiles, as well as operations in new defense areas such as outer space and cyberspace, the ministry said.