WASHINGTON — The Navy has relieved the two top officers of the destroyer John S. McCain, nearly two months after the ship collided with a tanker while approaching Singapore, leaving 10 sailors dead.

The commanding officer, Cmdr. Alfredo J. Sanchez, exercised “poor judgment,” and the executive officer, Cmdr. Jessie L. Sanchez, displayed “poor leadership of the ship’s training program,” according to a statement issued Wednesday by the Seventh Fleet in Yokosuka, Japan.

While an investigation is continuing into the Aug. 21 accident, the statement said that it was “evident the collision was preventable.” Both officers were relieved by Vice Adm. Phil Sawyer, the Seventh Fleet commander, “due to a loss of confidence.”

The dismissals are the latest fallout from the four Navy accidents this year in the western Pacific, including two fatal crashes: the John S. McCain’s collision and the destroyer Fitzgerald’s collision with a freighter in June near Tokyo.

Vice Adm. Joseph P. Aucoin, the former head of the Seventh Fleet, which is based in Japan and is the Navy’s largest overseas fleet, was removed in August in connection with the accidents. And the Navy’s top officer for ships worldwide, Vice Adm. Thomas S. Rowden, has said he would retire early.

In its initial response to the accidents, and after collecting lessons learned from a 24-hour suspension of ship operations to review safety and other standards, the Navy last month ordered a series of immediate changes in how its ships do business. They were seemingly obvious fixes that suggested why the Seventh Fleet believes the John S. McCain crash was avoidable.

Navy officials ordered more sleep for crews and no more 100-hour workweeks for sailors. Ships steaming in crowded waters, like those near Singapore and Tokyo, will now broadcast their positions, as do other vessels. And ships on which crews lack basic seamanship certification will probably stay in port until the problems are fixed.

Navy investigators have largely wrapped up their inquiries into what caused the fatal crashes, and Adm. John Richardson, the chief of naval operations, is expected to make public the findings and any recommendations in the next few weeks, Navy officials said. A comprehensive review of safety and operational standards will probably be completed next month.

Admiral Richardson offered a preview of what his focus may include in a statement last Friday to the entire Navy.

“When I hear about problems like persistent lack of sleep, consistently long work hours in port, problems in basic watchstanding, and more, it’s clear to me that much of the fix is with our junior leaders,” he said. “They can control so much if we give them clear guidance, responsibility, authority and accountability.”