The Japanese, U.S. and Philippine coast guards have held a joint drill in the South China Sea off the Bataan Peninsula west of Manila, as a part of the nations' first trilateral maritime exercises that began last week.

In part of a scenario demonstrated to reporters Tuesday, members of the coast guards trained on countering armed resistance on board a vessel suspected of carrying weapons of mass destruction, according to the Philippine Coast Guard.

Japan Coast Guard patrol vessel Akitsushima takes part in a joint drill with the U.S. and Philippine coast guards in Philippine waters in the South China Sea on June 6, 2023. (Kyodo)

A Philippine coast guard official said the three countries need to enhance maritime cooperation in engaging in search and rescue operations and coping with intrusion into territorial waters. China has increasingly been expanding its maritime activities in the region.

The trilateral exercise came as the United States and key ally Japan stepped up cooperation to assist Southeast Asian nations in enhancing their coast guard capabilities.

The U.S. Coast Guard deployed the 127-meter Stratton in the weeklong drill from Thursday last week and Japan Coast Guard deployed its 150-meter Akitsushima.

The drill involved four Philippine Coast Guard vessels, two of which are multi-role response vessels that Manila acquired from Tokyo as part of a project to improve the country's maritime capabilities.

The South China Sea is an important trade route where China, the Philippines and other Southeast Asian countries have overlapping claims.