Philippine and US marines are holding drills with members of Japan's Ground Self-Defense Force and the South Korean military in the Philippines.

The annual exercises have been conducted since 2016. The drills started on Monday. This is the first time that personnel from the four countries have taken part in the exercises.

A landing drill was held on Friday at a naval base in the province of Zambales. The province is located on the west coast of Luzon Island, which faces the South China Sea.

A joint unit of US and Philippine troops practiced procedures for landing on the beach using amphibious vehicles.

A drill simulating an attack involving chemical weapons was also carried out.

The US Marines and personnel from Japan's Ground Self-Defense Force showed the Philippine marines how to deal with such an attack.

GSDF Major Yonehara Kazufumi said the participants were able to deepen their understanding of one another by talking together.

President Ferdinand Marcos Jr. took office in the Philippines in June. China has been increasing its maritime activities in the South China Sea.

Observers say the Philippines is apparently trying to emphasize that it is cooperating with the US, Japan and South Korea.