India, Oct. 19 -- Japanese and US troops on Monday kicked off one of their largest joint exercises focusing on the defence of Japan's southwestern islands and showcasing advanced weapons systems in the face of growing tension in the region.

About 45,000 Japanese troops and 12,000 American service members are participating in the biennial Keen Sword 27. Seven other nations from the Indo-Pacific region and Europe are also taking part in some elements of the exercises, five of them - France, Germany, the Netherlands, New Zealand and the Philippines - for the first time, according to Japan's Joint Staff.

During the exercises, which run through October 29, the Japanese and US militaries will largely focus on defending Japan's southwestern is...