Two US Atlantic Fleet Los Angeles-class attack submarines, USS Helena and USS Annapolis, took part in the exercise. The Russian Pacific Ocean Fleet has said it would be closely monitoring the exercise. "Any action by foreign submarines in the vicinity of Russia's maritime borders naturally demands heightened scrutiny on our part, especially in the light of an accident involving a British submarine during a previous exercise," an official from the fleet said. He also said that the Pacific Fleet would use all its reconnaissance capability deployed on the Kamchatka Peninsula to track the activities of the U.S. exercise.