The head of the Navy’s Pacific Fleet announced Monday that he will retire after being passed over for the top job at U.S. Pacific Command.

Adm. Scott Swift’s announcement, made in a posting to Pacific Fleet’s website, marks the latest departure for regional and surface force commands in the wake of two fatal destroyer collisions this summer that killed 17 sailors.

Navy officials confirmed last week that Vice Adm. Thomas Rowden, the three-star in command of Naval Surface Force, would put in for early retirement, but declined to offer further details.

Also last week, newly installed 7th Fleet commander Vice Adm. Phillip Sawyer fired Task Force 70 commander Rear Adm. Charles Williams and Destroyer Squadron 15 head Capt. Jeffrey Bennett.

The destroyers Fitzgerald and John S. McCain, involved in the fatal collisions this summer less than two months apart, were overseen by those two units.

Before that, Vice Adm. Joseph Aucoin was fired as head of 7th Fleet just days after the McCain disaster in August.

In Monday’s statement, Swift said the service’s top officer, Chief of Naval Operations Adm. John Richardson, had informed him that he would not become the next commander of U.S. Pacific Command.

“In keeping with tradition and in loyalty to the Navy, I have submitted my request to retire,” Swift said. “I do so with great appreciation and gratitude for the honor of having served so many Sailors and their families for what will be 40 years in January.”

Being Pacific Fleet commander has in the past often led to leadership of a unified combatant command like PACOM.

Swift said he had not requested a retirement date “as there is much work to be done here in the Pacific area of responsibility.”

“Whether my timeline of remaining service is six weeks or six months, I will fill that time with the energy of an Ensign,” he said.

Pacific Fleet encompasses 100 million-square-miles, from Antarctica to the Arctic Circle and stretches from the American west coast to the Indian Ocean.

It oversees about 200 ships and boats, nearly 1,200 aircraft and more than 130,000 personnel.

Swift lamented in August the fact that the Fitzgerald collision off Japan in June that killed seven, and the McCain collision in August that claimed 10 sailors, happened while the Navy was conducting “the most basic of operations.”

In a private message to subordinates obtained by Navy Times in August, Swift said the fleet experienced “a series of unfortunate incidents, some of which claimed the lives of our shipmates,” while conducting basic duties like anchoring, navigation surface ship contact management and carrier qualifications.

Two destroyers colliding with commercial vessels this summer has sparked a service-wide review of how ship crews do business, and has raised questions about manning levels, training and readiness.