In the latest sign of Japan's increased activity in the disputed South China Sea, the Maritime Self-Defense Force's largest vessel, the helicopter carrier Kaga, linked up Friday for bilateral exercises with the U.S. Navy's Ronald Reagan aircraft carrier strike group, both countries' navies said.

The bilateral training is part of a rare, monthlong tour by the Kaga and two guided-missile destroyers that will see them make port calls in India, Sri Lanka, Singapore, Indonesia and the Philippines. As a part of the dispatch, which began Aug. 26 and will run through October, the vessels will also conduct joint exercises aimed at bolstering combat skills and improving cooperation with each country's navy, according to the Defense Ministry's Maritime Staff Office.

The office said late last month that the MSDF would also train with the U.S. Navy.