The U.S. Navy on Wednesday relieved the admiral in charge of the service’s 7th Fleet based in Japan due to “loss of confidence” in his ability to command, it said in a statement. The move comes after four embarrassing accidents this year, two of which killed sailors at sea.

Admiral Scott Swift, commander of the U.S. Pacific Fleet relieved Vice Adm. Joseph P. Aucoin from his duties at the 7th Fleet’s Yokosuka base in Japan. Rear Admiral Phil Sawyer, the Pacific Fleet’s deputy commander, will immediately take command. He had been scheduled to assume the post on Sept. 7.

The incidents include the deadly collision Monday of the destroyer USS John S. McCain with a much heavier oil tanker off Singapore, and a June 17 accident in which the destroyer USS Fitzgerald was ripped open by a larger Japanese container ship.

Seven sailors were killed in the Fitzgerald disaster, and at least some of the 10 sailors reported missing from the McCain are dead, Swift said Tuesday.

Vice Adm. Joseph Aucoin, commander of the U.S. 7th Fleet, holds a news conference after the collision of the USS Fitzgerald in Yokosuka, Japan, on June 18, 2017.

Aucoin has been the 7th Fleet commander since September 2015, and was previously the deputy chief of naval operations for warfare systems. His removal, first reported by the Wall Street Journal, is the highest profile in the Navy since the disasters occurred.

The collisions have shocked the Navy, where good seamanship and avoiding collisions are a fundamental expectation and demand. Adm. John M. Richardson, the chief of naval operations, announced Monday that he is ordering an “operational pause” across the globe in which commanders take a day or two each to make sure that sailors understand the fundamentals of good seamanship. He also directed a four-star officer, Adm. Phil Davidson of Fleet Forces Command, to launch a separate review of the 7th Fleet over the next few months to assess its culture, operations and readiness for missions.

Swift, who oversees the 7th Fleet as part of his role as Pacific Fleet commander, expanded the scope of that scrutiny Tuesday, ordering a second step to Richardson’s review that will include all Navy forces in the Pacific. It will include a “deliberate reset” for ships that focuses on navigation, maintaining mechanical systems and manning the ship’s bridge appropriately, Swift said.

“One tragedy like this is one too many, and while each of these four events is unique, they cannot be viewed in isolation,” Swift said of the 7th Fleet’s accidents. “I welcome the broad, comprehensive view announced by the chief of naval operations.”

So far this year, the fleet has faced four accidents that together have prompted questions about whether the sailors are being properly trained and supported. On May 9, the guided-missile cruiser Lake Champlain collided with a South Korean fishing vessel. On Jan. 31, the guided-missile cruiser Antietam ran aground in Tokyo Bay.

The 7th Fleet has headquarters in Yokosuka, Japan, and is responsible for an area that spans 36 maritime countries and 48 million square miles in the Pacific and Indian oceans, according to the Navy. The fleet has about 50 to 70 ships assigned to it, including about a dozen at sea at any time. The force’s missions range from responding to natural disasters to countering North Korean threats and Chinese audaciousness in the South China Sea, where Beijing has established new military bases.

“I think it’s important to note that the 7th Fleet is out there all the time, and it has been since World War II ended,” said retired Vice. Adm. Peter Daly, the chief executive officer of the U.S. Naval Institute. “It has been heel-to-toe. It has been ships there all the time, and ships deploying there all the time to augment the ships that are already there.”

Daly, who commanded everything from destroyers to carrier strike groups, said the recent incidents have highlighted what appears to be a disparity between how well ships that are based in Japan perform, as compared to ships that are based in the continental United States or Hawaii and set sail from there. The difference, Daly said, has sparked “a healthy concern” about why there is a difference between the two.

The unusual nature of the disasters even has prompted senior Navy leaders to rebut speculation that sabotage or a cyber attack may have caused the collisions. There is no indication that either occurred, Swift said again Tuesday.

The scrutiny comes as the Navy remains mired in a corruption scandal in which Malaysian defense contractor “Fat” Leonard Francis offered prostitutes, cash, gifts and other favors in exchange for information as he made hundreds of millions of dollars of business from the Navy. At least 19 defendants have been convicted, with at least 10 more cases pending.

But there’s another issue at play. Daly and another 7th Fleet veteran, Scott Cheney-Peters, said that years of the Navy reducing its number of ships has taxed the crews of those on the remaining vessels, as the Navy does more with less.

“Although many of these ships are more capable than their predecessors from the early 1990s, at some point the lower absolute number of ships taxes those remaining and their crews because they can only be in so many places and doing so many things at once,” said Cheney-Peters, who served on the Fitzgerald and later founded the Center for International Maritime Security, which facilitates discussion of naval issues.

“When I served in 7th Fleet aboard Fitzgerald a decade ago, the culture was of getting the mission done and taking care of your people, and only then taking care of yourself,” he said. “This is how it should be, but usually there wasn’t much time left for taking care of yourself, including for sleep.”