"An act of war."

This was how President Marcos described what the "willful" killing of a Filipino in the West Philippine Sea would mean to the Philippines, saying the country would respond accordingly if such an act happened.

Marcos said this during the interview portion of the 21st International Institute for Strategic Studies (IISS) Shangri-La Dialogue in Singapore on Friday evening, May 31.

During the interview portion, the President was asked about the actions that would prompt the Philippine government to invoke the decades-old Mutual Defense Treaty (MDT) with the United States of America (USA).

"What would happen if there was an incident that ended up killing a Filipino serviceman, be it a Coast Guard or in the military and part of the Navy? Well, that would certainly increase the level of response, and if by a willful act on a Filipino, not only serviceman but even a Filipino citizen," he said.

"If a Filipino citizen is killed by a willful act, that is, I think, a very, very close to what we define as an act of war, and therefore we will respond accordingly," he added.

Marcos said such an action would also increase the level of response not only from the Philippine government but also from its "treaty partners."

"We already have suffered injury, but thank God, we have not yet gotten to the point where any of our participants, civilian or otherwise, have been killed," he said.

"But once we get to that point, that is certainly we would have crossed the Rubicon and certainly crossed the Rubicon. Is that a red line? Almost certainly it’s going to be a red line," he added.

Despite this, President Marcos reiterated that the Philippines is committed to genuine peace in the region.

"We are determined to be a force for the good, a force for peace, a champion of regional and global unity, [and] a staunch defender of the rules-based international order," he said.