France is taking part in annual Philippine-US military exercises in the South China Sea for the first time. It comes amid soaring tensions between the Philippines and China over claims in disputed waters.
Manila has been looking to boost security ties with the US and its partners. France, which has territories in the South Pacific, is hoping to strengthen relations with the Philippines to deter China's growing influence.
More than 16,000 troops are taking part in the Balikatan joint exercises, which kicked off this week and will run through May 10.
Philippine naval officials said vessels from the three countries had started drills on Thursday within Manila's Exclusive Economic Zone. This overlaps with areas in the South China Sea that Beijing claims.
This is the first time the Balikatan exercises include such drills outside Philippine territorial waters.
Beijing has already been flexing its muscles within these contested areas. Its vessels have blocked Philippine supply ships and fired water cannon at them.
Earlier this month, the Philippines conducted a separate maritime exercise with the US, Japan and Australia, which was also aimed at keeping China in check.