PHILIPPINE President Ferdinand R. Marcos, Jr. on Monday said his government is considering including Japan in its annual military exercises with the United States, amid worsening tensions in the South China Sea.

“We’ll see about that,” he told foreign journalists at a news briefing in Manila. “That may be something that we can study. I for one have no objection to such an idea.”

“I don’t see any reason why Japan should not be part of all those exercises in the future,” he added.

Mr. Marcos also said the three-way agreement among his country, the US and Japan was not directed at anyone and only seeks to boost relations among the three nations.

“Really, what the aim of the trilateral agreement — but it is not only the US Japan and the Philippines — is really to maintain the freedom of navigation along the South China Sea,” he said.

He met with US President Joseph R. Biden and Japanese Prime Minister Fumio Kishida in the nations’ first trilateral summit in Washington last week.

The leaders committed to boost ties in maritime security amid China’s growing assertiveness in the waterway.

The death of a Filipino soldier in the South China Sea could be grounds to invoke a mutual defense treaty with the US, Mr. Marcos told reporters.

He also said the Philippines had no plans to further expand US access to military bases in the Philippines.

Last year, the Philippines gave the US access to four more military bases on top of the five existing ones under their Enhanced Defense Cooperation Agreement (EDCA).

The Philippines and the US are set to hold their annual Balikatan (shoulder-to-shoulder) military exercises on April 22 to May 18, with 5,000 Filipino soldiers and 11,000 American servicemen expected to participate.

For the first time, it will be held beyond the Philippines’ 12-nautical mile territorial waters.

The Philippine President said the military exercises would tackle more areas of defense including cybersecurity.

He added that negotiations with Japan for a Reciprocal Access Agreement are almost done, citing the need to work out the logistics of the agreement.

“There aren’t any real conflicts in principle,” Mr. Marcos said. “It’s just a question of getting the language down and defining precisely how it’s going to work.”

Both countries started negotiations on the agreement last year, which would allow forces to be deployed on each other’s soil.

The pact would be submitted to the Philippine Senate and Japanese Legislature for approval.

Tensions between the Philippines and China have worsened in the past year as Beijing continues to block Manila’s resupply missions to Second Thomas Shoal, where it grounded a World War II-era ship in 1999 to assert its sovereignty.

US Defense Secretary Lloyd J. Austin told Mr. Marcos at the weekend the Biden government was seeking a $128-million budget to carry out EDCA projects.

Last week, Washington, Tokyo, Canberra and Manila held joint military drills within the Philippines’ exclusive economic zone in the South China Sea. — John Victor D. Ordoñez