A Maritime Self-Defense Force flotilla of three ships arrived in the Philippines early Sunday on a goodwill visit — the first to include a Japanese submarine in 15 years — amid China’s growing assertiveness in the region.

The training submarine Oyashio, accompanied by the destroyers Ariake and Setogiri, made a port call at Subic Bay, home of a former U.S. naval base, ahead of planned open sea drills. Some 500 Japanese personnel, including 55 officer candidates, are taking part in the confidence-building exercise.

Philippine Navy public affairs officer Capt. Lued Lincuna said the three MSDF vessels would be staying in Subic Bay until Wednesday.