Ten sailors assigned to the ship were missing following the accident, and the Navy has reported that "some" remains have been recovered, Adm. Scott Swift, commander of the US Pacific Fleet, said Tuesday. Swift will be in Japan today to meet 7th Fleet commanders and families from the affected warship.
A statement from the 7th fleet said Aucoin was relieved "due to a loss of confidence in his ability to command."
Rear Adm. Phil Sawyer, who has already been nominated and confirmed for the position and promotion to Vice Adm., will assume command immediately.
US Navy and Marine Corps divers found the remains in the sealed compartments aboard the McCain after it docked at a naval base in Singapore, said Swift. US military divers continue to search the flooded areas of the McCain.
The Royal Malaysian Navy has located one body at sea, and officials are working to determine whether it is one of the missing sailors, he said. Ships and planes are scouring the seas east of Singapore.
"Until we have exhausted any potential of recovering survivors or bodies, the search and rescue efforts will continue," Swift said.
The White House expressed its "great sadness" about the incident. "As the Navy begins the process of recovering our fallen sailors, our thoughts and prayers go out to their families and friends," the statement said.
As well as providing material support from the amphibious assault ship the USS America, the 7th Fleet statement said that the Navy was providing mental health support and other counseling and medical resources.
"Although most people will spontaneously emotionally recover, there may be some that experience significant psychological distress and may need attention from mental health professionals," Lt. Cmdr. Carlos Coleman, Medical Service Corps said. "We want to do everything we can to help them manage the stress of this tragic event."
The McCain suffered a steering failure as the warship was beginning its approach into the Strait of Malacca, before colliding with the tanker,
a Navy official told CNN.
The official said it was unclear why the crew couldn't use the ship's backup steering systems to maintain control.
Reporters on Tuesday asked about the possibility that the McCain could have had its computer systems compromised.
Swift said that, while there were "no indications of that as of yet ... we are not taking any consideration off the table and every scenario will be reviewed and investigated in detail."
Adm. John Richardson, chief of naval operations had previously indicated on Twitter that the possibility of a cyberattack, however slight, would be investigated.
Carl Schuster, a Hawaii Pacific University professor and former director of operations at the US Pacific Command's Joint Intelligence Center, said that he thought it was unlikely that the ship would have been hacked.
"Navigating a ship in a shipping channel is a manual operation. It comes down to watch attention and awareness. It's a training procedure issue and a watch qualification issue," he said.
He added that even if the steering had been compromised it would be possible for the McCain to outrun the tanker, and that some degree of directionality would be possible by changing the speed of the port and starboard propellers.
The "traffic situation" in the shipping channel at that time should be the focus of investigation, Ridzwan Rahmat, a senior defense and security analyst at Jane's suggests.
"The signs were that the merchant ship was in compliance and the damage on the USS John S. McCain suggests that it wasn't in compliance" of traffic rules at the time, he said.
The collision prompted the Navy to order a rare, one-day operational pause
The pause is a one-day, safety stand-down that would be done at the discretion of individual commands, a US defense official told CNN. It will be done rotationally, with units standing down for a 24-hour period, so as to minimize the effect on operational capability.
Swift said the Pacific Fleet will complete the operational pause by next Monday.
"The question is: are naval operations (in the Pacific theater) stretched too thin; is the tempo of operations sustainable," said Rahmat.
Aucoin's role has come under scrutiny since a spate of incidents in the Pacific theater, including another at-sea collision between a US Navy destroyer, the USS Fitzgerald, and a cargo ship off Japan's Izu Peninsula.
"This trend demands more forceful action," Richardson said.
Spate of incidents
"It's peculiar that so many (incidents) have occurred in a short period of time, which suggests that there could be systemic (problems)," Rahmat said.
He suggests it could be a "problem with certification of crew: are they capable enough to be on the bridge, to perform maneuvers?"
The Fitzgerald incident, on June 17, caused the deaths of seven US sailors.
Speaking shortly after that incident, Aucoin told reporters, alongside the ship at Yokosuka Naval Base in Japan, that the loss of sailors under his command "is something we all feel."
"We have found a number of the remains ... of our missing shipmates, and our deepest sympathies go out to the families of those shipmates," he said.
Findings in that investigation suggested the accident was caused by multiple errors by the Fitzgerald's crew and a failure to take action in the minutes leading to the collision, according to two defense officials.