The United States Senate has reaffirmed its commitment to the 74-year-old Mutual Defense Treaty (MDT) with the country through a bipartisan resolution condemning China’s “unprovoked aggression” in the West Philippine Sea.
Filed on September 18 by Sen. Pete Ricketts of Nebraska with 11 co-sponsors, Senate Resolution 409 denounces Beijing’s repeated harassment of Philippine Coast Guard vessels and declares that the MDT applies to attacks against Philippine forces, ships, and aircraft “anywhere in the South China Sea.”
The resolution cites several incidents in 2024 and 2025 that underscore China’s increasing assertiveness, including the April incident when Chinese forces planted a flag on Sandy Cay near Pag-asa Island, and the August 11 collision near Scarborough Shoal involving Chinese vessels that blocked a Philippine humanitarian mission.
It also condemns Beijing’s use of water cannons, blockades, and military-grade lasers against Philippine resupply missions at Ayungin Shoal, as well as China’s move to declare Scarborough Reef a “national nature reserve,” calling these actions coercive and destabilizing.
The measure urges the White House to take “appropriate and necessary actions” to counter Chinese escalation and pledges expanded joint patrols, cyber operations, and support for the Philippines’ defense modernization.
It also pushes for stronger cooperation with Japan, South Korea, and Australia to maintain regional stability and uphold freedom of navigation.
Signed in 1951, the MDT requires the Philippines and the United States to act in case of an external armed attack in the Pacific.
The pact laid the foundation for subsequent defense agreements, including the Enhanced Defense Cooperation Agreement (EDCA), which Manila expanded in 2023 to include four additional sites.
The resolution comes amid intensified US-Philippine defense cooperation. Earlier this year, the Balikatan 2025 exercises featured the first deployment of the U.S. Navy-Marine Expeditionary Ship Interdiction System in the Philippines.
In March, U.S. Defense Secretary Pete Hegseth visited Manila and pledged stronger support for the country’s defense industry.
