Admiral Harry Harris, commander of the Pacific Command, reaffirmed Washington’s commitment Wednesday to defend the small islands owned by Japan in the East China Sea under a bilateral security treaty if attacked, while taking the rare step of naming China as the possible aggressor.

At an event at a Washington think tank, Harris said, “We will clearly defend them if they are attacked by China.” He is referring to the Senkakus, a group of islets claimed by China, which calls them the Diaoyu.

U.S. leaders including President Barack Obama have already stated that the 1960 security treaty, which obliges the U.S. military to defend Japan including Senkakus if it is attacked.

Washington says it does not take sides on the conflicting claims to sovereignty over the islets.