China deploys boats to patrol the busy waterway and has built artificial islands that it has militarised to reinforce its claims to almost the entire sea.
It has also ignored an international tribunal ruling that its claims have no legal basis.
During their meeting last week, Marcos and Xi agreed that their disputes in the South China Sea should not be the “defining element” of their relationship, Marcos said earlier.
In Hawaii, Marcos hailed the “concrete support” for the Philippines from its longtime ally, the United States, as well as Australia, South Korea and Japan, which have been deepening their defence cooperation with the Southeast Asian nation in the face of China’s growing military might.