CBS News National Security Correspondent David Martin reports the high alert has been ordered in response to what Pentagon officials call specific and credible intelligence reports of plans for another terrorist attack.
The alert status, known as condition Delta, is equivalent to being placed on a battle footing. In addition, the U.S. Embassy in Qatar has been closed down.
The State Department said the U.S. Embassy in Jakarta was also closing for the rest of the week because of a specific threat against the mission in the Indonesian capital.
"Given the circumstances the recent attack on the Cole and the generally higher level of threat throughout the region we thought it was simply the prudent thing to do," Pentagon spokesman Craig Quigley said.
Intelligence sources say the evidence of plans for a terrorist attack may point to groups with links to suspected terrorist mastermind Osama bin Laden. That has touched off a debate within the Clinton administration on whether to launch preemptive strikes on bin Laden's bases in Afghanistan.
Quigley said the decision to raise alert levels was based on intelligence reports of "multiple threats" from "multiple sources." He would not be more specific.
The Cole was at alert status Bravo when it entered Aden harbor. In fact, it was not until many days after the Oct. 12 bombing that machine gun positions were visibly posted on the Cole's deck.
But a machine gun probably wouldn't have stopped the suicide attack that killed 17 sailors because the craft carrying the explosives simply was not recognized as a threat.
USS Cole crew member Raymond Mooney, who was wounded in the attack, says, "I saw the boat come up and they waved at me. Actually they waved at me first and I waved back at them."
Mooney, a Navy seaman who was a gas services systems technician on the Cole, was wounded in the explosion. Mooney believes he was one of only a few people who saw the boat as it pulled alongside the Navy destroyer. He believed at the time it was a service ship, perhaps collecting garbage.
"They were coming in a little faster, you know, they were traveling a little faster than every boat in the harbor and they were coming right at us," he said.
An investigation will have to determine whether the captain and crew of the Cole are to blame for letting down their guard.
Mooney says he and his shipmates had been warned earlier in the year by a high-ranking naval officer that their mission was one which would place them in constant danger.
"We had some important admiral come and talk to us and say 'You're gonna be targeted every day. It's not a safe environment,' " recalled Mooney, who adds that he'd like to see the U.S. punish whoever is responsible for the attack on the Cole.
In the meantime, U.S. forces aren't taking any chances, although they can not stay at such high states of alert for very long before they become routine.
In the immediate aftermath of the blast on the Cole, the State Department issued a worldwide warning to American travelers and closed several embassies throughout the world for a number of days.
The United States has 916 servicemen and women in Bahrain, a Persian Gulf island chain of 634,000 people that is roughly four times the size of Washington, D.C. It is the headquarters for the U.S. Central Command's naval forces and for the U.S. Navy's Fifth Fleet.
In Manama, Bahrain, the Bahrain School, whose students are mostly American, has been shut down temporarily because of tension caused by clashes between Palestinians and Israeli soldiers. The U.S. Embassy in Bahrain is furthermore urging Americans to avoid large gatherings where they could be vulnerable to attack.
The American military presence there consists of 667 naval personnel, 15 from the Army, 216 marines and 18 from the Air Force.
Only 25 American military personnel are in Qatar, 23 of them from the Army and two from the Air Force. Qatar, about the size of Connecticut, is a peninsular country on the east coast of Saudi Arabia with a population of over 744,000.