INTRO: The apparent terrorist attack on a U-S destroyer in Yemen has underscored one of the vulnerabilities of modern warships. V-O-A Pentagon Correspondent Alex Belida explains.

TEXT: She was, in the words of top Navy officers, a ship "built to fight."

Bristling with powerful missiles and guns, sophisticated radar systems and countermeasure devices, the billion dollar destroyer U-S-S Cole was considered capable of taking on threats from any enemy aircraft, missile, submarine or ship.

But Pentagon authorities now acknowledge the Cole, and its crew of about 350, were all but defenseless against an attack by a small boat in a busy harbor especially a boat sent out by harbor authorities to assist in her mooring for a brief refueling stop.

It was just such a small boat, apparently loaded with high explosives, that pulled aside the U-S destroyer in Aden on Thursday and blasted a massive, gaping hole in her side, killing or injuring more than 50 U-S sailors.

That it was a deliberate attack seems clear. According to a Navy spokeswoman, an ordnance expert who has examined the damaged hull has confirmed the explosion occurred outside the ship and could not have been caused by any on-board problem.

Still, it is not known conclusively who was behind the bombing or why. Navy officials say there had been no specific threats made against the Cole ahead of its arrival. They say other recent refueling visits by U-S vessels had occurred without incident.

Nevertheless, intelligence experts say Yemen has for some time been considered a haven for terrorists, including some thought to have links to Osama bin-Laden. He is the Islamic militant accused of orchestrating the 1998 bomb attacks on U-S embassies in Kenya and Tanzania.

The explosion on the destroyer Cole is the most serious terrorist attack against U-S interests since the embassy bombings.

Top U-S officials have vowed to hunt down and punish those found to be responsible.

In the meantime, the Navy has disclosed that a special 50-member anti-terrorist security team has arrived in Aden to augment security for the Cole as damage repair efforts continue. (Signed)