The first-ever trilateral summit between US President Joe Biden, Japanese Prime Minister Fumio Kishida, and Philippine President Ferdinand Marcos Jr. comes as the Philippines faces escalating maritime tension with China over their contested South China Sea claims.

Biden wants to show that the three maritime democracies are unified as they face aggressive Chinese action against the Philippine Coast Guard and its supply vessels off the disputed Second Thomas Shoal in the South China Sea, according to a senior Biden administration official.

Japan has sold coastal radars to the Philippines and is now negotiating a defense agreement that would allow their troops to visit each other’s turf for joint military exercises.

The trilateral comes eight months after Biden hosted a meeting with leaders from Japan and South Korea at Camp David.