Aircraft and vessels have been looking for the missing personnel since the two ships crashed in the pre-dawn hours Saturday.
The Fitzgerald changed its home port to Yokosuka, Japan, in 2004 as part of a deployment "to counter ballistic missile threats worldwide", according to the official history.
Benson, the Fitzgerald's commander, was new to the position, having taken command of the vessel May 13 after serving as the ship's executive officer, or second in command, since November 2015, the Navy said last month.
"It remains uncertain how long it will take to gain access to the spaces once the ship is pier side.to methodically continue the search for the missing", the statement said.
At around 29,000 tons displacement, the ship dwarfs the 8,315-ton United States warship, and was carrying 1,080 containers from the port of Nagoya to Tokyo.
The names of missing sailors were being withheld until families had been notified.
The USS Fitzgerald was back at its home port in Yokosuka Naval Base south of Tokyo on Saturday with extensive damage to its hull.
More than 200 sailors would have been asleep on the ship at the time of the collision.
The Navy said that the USS Fitzgerald collided with a merchant ship 56 nautical miles southwest of Yokosuka, Japan, a city south of Tokyo that is home to a major U.S. Naval base.
In a statement released on social media, US Navy operations chief Adm John Richardson said: "As more information is learnt we will be sure to share it with the Fitzgerald families and when appropriate the public. Thank you to our Japanese allies for their assistance", US President Donald Trump tweeted.
The USS Fitzgerald collided with a container ship four times its size off the coast of Japan before dawn Saturday.
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The U.S. Navy is searching for missing sailors after one of its ships and a merchant vessel collided off the coast of Japan.
The USS Fitzgerald was damaged both above and below the water line.
The ship arrived at Tokyo Bay later in the day.
The waterways approaching Tokyo Bay are busy with commercial vessels sailing to and from Japan's two biggest container ports in Tokyo and Yokohama.
Seven US crewmembers are missing and at least three were hurt in the accident, according to the US Navy said. Three, including the captain, have been injured. It is chartered by Japanese shipping company Nippon Yusen Kabushiki Kaisha (NYK) and owned by Dainichi-Invest Corporation, NYK said.
Japan's Coast Guard said that none of the 20 crew members aboard the merchant vessel was injured.
An investigation was underway to determine what caused the nighttime collision between the destroyer and the container ship.
Footage and images from Japanese broadcaster NHK showed that the Fitzgerald had suffered substantial damage to the ship's starboard side.
The Navy's 7th Fleet reported the developments in an update on the stricken ship that was nearing the port of Yokosuka in Japan.
"The Embassy said that they are ready to extend all necessary assistance to Filipino seamen onboard the ship", he added.
The larger size of the container ship could have left the smaller USA destroyer vulnerable in the collision, Schuster said.