A Navy official said the watch team aboard the San Jacinto saw a periscope rise from the water about 100 to 200 yards (metres) ahead of the vessel during the exercise. The cruiser ordered “all back,” but the San Jacinto still collided with the submarine.

The collision caused the collapse of the cruiser’s sonar dome, a bulbous-shaped device on the bow of the ship beneath the water line, the Navy official said on condition of anonymity.

The rubber dome houses some of the vessel’s electronic navigation, detection and ranging equipment.

The ships were part of a strike group led by the aircraft carrier USS Harry S. Truman. The Truman was in the area and provided support to the vessels.