President Joe Biden made “ironclad” defense pledges to Japan and the Philippines on Thursday as he hosted his counterparts amid growing tensions with Beijing, whose actions the three leaders described as “dangerous and aggressive.”

Biden cemented the United States’ security commitments in the South China Sea, as repeated confrontations between Chinese and Philippine vessels have stoked fears of wider conflict.

“Any attack on Philippine aircraft, vessels or armed forces in the South China Sea would invoke our mutual defense treaty,” Biden said as he met Philippines President Ferdinand Marcos Jr and Japanese Prime Minister Fumio Kishida at the White House.