TOKYO - President Rodrigo Duterte is expected to clarify his remarks against the United States and how these would affect Japan's interests during a private meeting with Japanese Prime Minister Shinzo Abe here this week.

The "four eyes" meeting at the Prime Minister's office on Wednesday will be one of three meetings on the two country's strategic partnership, including defense cooperation, an official helping arrange the meeting told ABS-CBN News.

"We expect that they will ask him to explain the breadth and depth of his statements against the US," according to the official, who asked not to be named for lack of authority to speak to media.

"They would like to know what he really wants."

The Philippine side was informed about Abe's desire for a private meeting while Duterte was winding up his state visit in Beijing last week, the official said.

Duterte and Abe will sit down with other governments officials in an expanded bilateral meeting then issue a joint statement on Wednesday.

Duterte, who is set to arrive in Tokyo Tuesday afternoon, earlier announced his economic and military "separation" from the United States.

But he later clarified that he was not severing ties with the Philippines' long-time ally despite his pivot to Washington's rival China.

Duterte's clarification will be important given the Philippines' role in its alliance with Tokyo and the US in the region, said Jay Batongbacal, director of the UP Institute for Maritime Affairs and Law of the Sea.

"Definitely, Japan will be concerned, or probably is the most concerned nation when it comes to say, China's increasing dominance over the South China Sea," he told ABS-CBN News.

"They're the ones who will be most directly hit by it actually. So that is their key interest."

Under a defense agreement signed with former President Benigno Aquino III, Japan pledged to beef up the Philippines' maritime capability in response to Beijing's assertiveness in the South China Sea.

In August, Japan delivered the first in a 10-vessel loan for the Philippine Coast Guard. It is also leasing Beechcraft TC-90 King Air Planes to the Philippines.

"There's a lot of interest in defense cooperation," said Consul General Marian Jocelyn Tirol-Ignacio."