The BRP Miguel Malvar took on water while being towed ahead of a live-fire drill in the South China Sea.
Russian President Vladimir Putin said the war games, which span both hemispheres, are the largest of their kind in three decades.
Two decommissioned U.S. Navy vessels were sent to the bottom of the Pacific Ocean in live-fire sinking drills.
The drills come a year after the Philippines approved a wider U.S. military presence in the archipelago, which China opposed.
