About 70 US navy ships, including the aircraft carrier USS Ronald Reagan, were in southeastern US ports threatened by Hurricane Isabel, a category four storm packing 240 kilometer (150 mile) per hour winds.
"What they're doing is looking at the storm's track, looking at the storm's speed, trying to see what decision makes the most sense," said Ted Brown, an Atlantic Fleet spokesman at Norfolk, Virginia.
A decision on whether to move the fleet from port was expected later in the day, he said.
The last time the Atlantic Fleet scattered from its main base in Norfolk to avoid a storm was in 1999, he said.
"It's very expensive to get that many ships under way," Brown said.
"We don't want to make the wrong decision, but obviously these ships are much more capable of riding out a storm at sea where they can maneuver around the path of storm than they are sitting at pier where they can do considerable damage," he said.
Not all 70 ships now in port would be able to get underway because some of them are undergoing repair in shipyards, he said.
"Any ship that can get underway, if the order comes to sortie, will get underway," he said.