SINGAPORE — Speaking at the Shangri-La Dialogue Defense Summit in Southeast Asia, Philippine President Ferdinand Marcos Jr. laid out a nearly black-and-white standard for what would be considered an act of war by China.
The remarks came in response to questions about Second Thomas Shoal, a reef in the South China Sea where the Philippines has a base. Beijing claims the area, contrary to a 2016 UN ruling, and has launched monthly attacks on Philippine ships that resupply the base, including firing water cannons and ramming Philippine vessels.
But if the aggression led to the deaths of Filipino civilians, it “would come very close to what we would define as an act of war,” Marcos said.
It’s more than just semantics.
The Philippines and the United States have a mutual defense treaty dating back to the 1950s, which has kept Chinese actions around the reef in the “gray zone,” short of full-scale conflict. China has used its coast guard, rather than its navy, to seize Philippine ships, and those forces have injured but not killed Filipinos.
So the question is: what would Manila define as an act of war rather than harassment, and what could potentially spark war between the US and China?
Regarding Chinese troops killing Filipinos, President Marcos said, “That would almost certainly be a red line that should not be crossed.”
Asked after the weekend speech whether the US would also consider this an act of war, US Secretary of Defense Lloyd Austin said he would not speculate on hypothetical situations.
“We will continue to emphasize that our commitment to the Mutual Defense Treaty remains steadfast,” Austin said.
The keynote speech marked an important address for President Marcos and for the Philippines more broadly, as Manila seeks to deepen security ties with like-minded nations such as Washington, Japan and Australia and play a larger role in regional security.
Greg Poling, a Southeast Asia expert at the International Center for Strategic Studies, said no issue unites the coalition more than the South China Sea.
“The South China Sea resonates in some way with nearly every U.S. ally and partner, and even countries outside the region, because it’s a question of law across the board,” Poling said. “Everybody agrees that China is in the wrong.”
This story has been updated to include comments from Defense Secretary Lloyd Austin.
Noah Robertson is a Pentagon reporter for Defense News. He previously covered national security for The Christian Science Monitor. He earned a bachelor’s degree in English and political science from the College of William and Mary in his hometown of Williamsburg, Virginia.
