JAKARTA, Indonesia — A trilateral meeting among the United States, Japan and the Philippines is in the works this week to discuss several areas of concern, Philippine Ambassador to the US Jose Manuel Romualdez revealed.

In a chance interview with Malacañang reporters late Tuesday evening, Romualdez said the three countries sought a meeting on the sidelines of the ongoing 43rd ASEAN Summit.

Romualdez, however, said they were still working out the details due to the tight schedules of US Vice President Kamala Harris and Japanese Prime Minister Fumio Kishida.

"The schedules are a bit tight for both Japan and the United States," he said.

"Vice President Harris just arrived this evening (Wednesday) and she's having a whole day meeting tomorrow. So, they're trying to look for the time," he added.

If the meeting does push through, Romualdez said the agenda will likely focus on cooperation among the three countries, especially on economic security.

"We're all allies basically, Japan, the United States and the Philippines," Romualdez said. "So I'm sure obviously the West Philippine Sea will most likely be part of the discussion, but mostly on cooperation, and how Japan, the United States, and the Philippines can work together, especially in the area of economic security, which is also very important for us."

The West Philippine Sea in the Philippines' exclusive economic zone is being claimed by China and several other countries. The Philippines has accused China of militarizing the sea and of violating its sovereignty.

Romualdez said he did not think China would take issue with the trilateral meeting.

"I don't think there's any… it's nothing new that the countries… in meetings like this, in summits like this, there's always a lot of bilateral meetings between so many countries," Romualdez said.

"I know that people are putting meaning to it… a special meaning to do it because of the situation in our part of the world, but at the end of the day, it is really a meeting of friends and allies and partners," he said.