The Fitzgerald was about 64 miles south of Yokosuka when the Crystal rammed nose-first into the destroyer’s starboard, or right, side. It was a clear night, but the crash occurred in a busy sea lane.
Photographs showed the side of the Fitzgerald caved in about a third of the way back. The Navy said the collision inflicted significant damage to the destroyer above and below the water line, flooding berths, a machinery area and the radio room. The Crystal, at 730 feet in length, is more than 200 feet longer than the Fitzgerald and, with its load of shipping containers, would weigh several times as much.
The cause of the collision was unclear. Under international maritime rules, a vessel is supposed to give way to another one on its starboard side, and the damage indicates that the Crystal was to the Fitzgerald’s starboard, and therefore had the right of way.
But maritime experts cautioned that many other factors could have led to a crash. Marine traffic records show the Crystal made a series of sharp turns about 25 minutes before the collision, which in crowded seas could cause a cascade of maneuvers by other vessels.
“Those are very high-traffic-density areas near coastal waters,” said Bill Doherty, a ship safety investigator and auditor with a long career of service on naval warships. “When a big ship like that makes a drastic change in a high traffic area, that has to be explained.”
Sean P. Tortora, a veteran merchant marine captain and consultant who said he had sailed through the area of the collision many times, said that evidence suggested the Fitzgerald was at fault.
Captain Tortora described the collision as a “T-bone” in which the bow of the Crystal hit the starboard side of the Fitzgerald. “From what I’ve seen, the Fitzgerald should have given way and passed to the stern of the container ship,” he said.
He added that a common cause of collisions, at sea or on the simulators used for training, is a misjudgment of distance and speed on the part of a captain trying to cross in front of another vessel. “They think they can make it and they make a run for it,” Captian Tortora said.
Another possibility, Mr. Doherty said, is that one or both vessels were acting “in extremis,” or ahead of what appears to be an imminent collision. “At that point, both vessels are burdened, and then both vessels, by law, are required to immediately take the best action to aid to avert a collision,” he said.
Asked about Captain Tortora’s comments, a Navy spokesman, Capt. Charles W. Brown, said it was premature to address the cause of the collision.
“At this point our foremost concern is the search for the missing sailors and the well-being of the crew,” he said.
Japanese Coast Guard officials were questioning members of the Crystal’s crew, and were looking into whether the incident was caused by professional negligence, Masayuki Obara, a regional Coast Guard official, told The Associated Press.
A former director of the National Transportation Safety Board’s office of marine safety, Marjorie Murtagh Cooke, said it could take a year or more to determine what happened.
“We don’t know what information was available to each of these vessels at the time,” Ms. Cooke said. “Was all of their equipment working? Was one vessel at anchor and the other moving? There are just so many facts that we don’t have yet.”
The Fitzgerald had recently participated in military exercises with two American aircraft carriers and ships from the Japan Maritime Self-Defense Force, as that country’s navy is known.
“Thoughts and prayers with the sailors of USS Fitzgerald and their families,” President Trump wrote on Twitter on Saturday. “Thank you to our Japanese allies for their assistance.”
The Crystal, chartered by Nippon Yusen, a Japanese shipping company, had about 20 Filipino crew members on board, the company said in a statement. The cargo ship was heading toward Tokyo at the time of the collision, after making a stop on Friday at Nagoya, Japan.
Marc Tuell, who served as a personnel specialist on the Fitzgerald from 2010 to 2013, found it disturbing to watch the video of the damaged ship being towed to port in Japan.
“It’s pretty heart-wrenching, having walked those decks for three years,” Mr. Tuell said. He retired from the Navy and lives in Deltona, Fla. “Heaven forbid that those seven souls are lost.”