The Navy’s top admiral on Monday ordered a fleetwide review of seamanship and training in the Pacific after the service’s fourth major accident at sea this year, a collision of the USS John S. McCain off Singapore that left 10 sailors missing.

The accident, which occurred Monday east of the Strait of Malacca about 5:24 a.m. local time, involving an oil tanker three times the size of the guided-missile destroyer, could be the Navy’s second deadly ship collision in about two months. On June 17, the destroyer USS Fitzgerald collided off the coast of Japan with a much heavier container ship, drowning seven sailors after a berthing compartment inside the ship flooded in less than a minute.

In addition, the guided-missile cruiser USS Lake Champlain collided with a South Korean fishing vessel on May 9 off the Korean Peninsula and the guided-missile cruiser USS Antietam ran aground Jan. 31 in Tokyo Bay, near its home port of Yokosuka, Japan.