U.S. President Joe Biden and Philippine leader Ferdinand Marcos Jr. were set to agree Monday on the need to bolster trilateral security cooperation with Japan, senior U.S. officials said, in a move that could pave the way for a reported tripartite framework amid rising Chinese assertiveness in the Indo-Pacific region.

Marcos was due to meet Biden for a summit Monday in Washington, the second day of a four-day U.S. visit — the first by a Philippine president in more than 10 years.

Both Tokyo and Washington have sought closer defense ties with Manila as concerns mount over Beijing’s military moves near democratic Taiwan. The Philippines, which is separated from Taiwan by the Bashi Channel, is also on the front lines of the disputed South China Sea.