Adm. Mike Mullen also said there shouldn't be any rush to terminate military assistance to President Hosni Mubarak's government.
Mullen also reinforced President Barack Obama's call for a "peaceful, nonviolent transition" and said that decision ultimately must be made by the Egyptian people and their government.
As for U.S. assistance to Egypt, which has averaged about $1.3 billion a year, Mullen said Congress shouldn't move too hastily to cancel the program. Mullen says on ABC's "Good Morning America" he would "caution against doing anything until we know what's really going on."
Mullen said he has been in regular communication with his Egyptian counterpart and he doesn't believe the army will attack the demonstrators. He said military personnel in Egypt have sought to remain neutral and "they really want to continue to do that."
The Navy admiral said the United States is in a higher state of "awareness" but not in a higher state of alert.