"This was the most thorough search we have ever conducted," McClelland said at a news conference. "That patch of ocean was repeatedly searched, exhaustively, and with great care."
He said even when the active search is called off, the Coast Guard will maintain a presence in the area where the Ehime Maruwent down.
At that point, the U.S. Navy will take over search and recovery operations, and will send a remote operated vehicle (ROV) known as Scorpio II underwater at the site of the collision to determine the location of the ship and the feasibility of a recovery operation.
The search began Friday after the USS Greeneville surfaced in the Pacific Ocean, roughly 10 miles off the coast, and struck the Japanese vessel, which was carrying 35 people. Twenty-six people from the ship were rescued from lifeboats.
Despite an extensive search that covered an area as large as the state of Connecticut and involved equipment and personnel from both the Coast Guard and the Navy, there have been no signs of the missing nine, including four high school students.
McClelland said 12 ships and 11 aircraft from both the Navy and Coast Guard covered 72 search areas, totaling 38,000 square kilometers.
The ship was carrying the high school students on a field trip to learn about commercial fishing.
In Tokyo, foreign ministry officials said the head of Japan's North American Affairs Bureau contacted a top official at the U.S. embassy there to strongly request that Washington reconsider the Coast Guard's earlier decision to call off the search and rescue mission.
Fifteen crew members from the Japanese trawler arrived back in Japan on Thursday.
When asked how the families of the nine missing reacted to news that the search was going to be suspended shortly, McClelland said they took it well.
"They were very understanding and there was no disagreement to that," he said.
