The 2nd Marine Division based in Camp Lejeune, North Carolina, has received orders to deploy a few hundred headquarters staff for a joint task force for the Horn of Africa, the officials said.

A strike force of some 800 US special operations forces and marines already are on station in the former French colony of Djibouti for possible use against al-Qaeda in the area. No operations have been launched so far, and the forces in Djibouti have engaged mainly in training and expanding contact with government forces in Somalia, Ethiopia, Eritrea, Kenya and Yemen, they said.

But they are on the lookout for al-Qaeda leaders, particularly in Yemen, whose lawless border region is the ancestral home of al-Qaeda leader Osama bin Laden and a potential al-Qaeda stronghold.

Yemen was the scene of a terrorist attack on a French oil tanker earlier this month, and the US Navy has warned shippers of the threat of attack off the Horn of Africa.

"If something breaks, and you find something and go after it, you have to have someone focused on it," a defense official said, explaining the decision to create a joint task force.

More broadly though, the move will allow General Tommy Franks, the commander of US forces in the Gulf, to concentrate on planning for possible military action in Iraq, said the official, who asked not to be named.

It was not immediately known if the joint task force will be headquartered in Djibouti or aboard a US navy ship.

The Pentagon earlier this year set up a similar task force in Afghanistan to direct US operations there and ease the demands on Franks, who would likely command any US invasion of Iraq.

US forces in the region now number more than 60,000, climbing in recent days as forces flow into Kuwait from Europe and the United States, and as the navy rotates its warships into the region.

"Some helicopters and some headquarters elements are starting to arrive in Kuwait," said the official.

He was referring to 24 AH-64 Apache helicopters from an army aviation regiment and headquarters staff from the fifth Corps in Germany, and headquarters staff of the first Marine Expeditionary Force based in Camp Pendleton, California.

An amphibious assault group led by the helicopter carrier USS Nassau transited the Red Sea this week with a contingent of some 2,200 Marines, relieving an amphibious ready group led by the USS Belleau Wood.

In another sign of stepped up preparations for war in the Gulf, the head of the US missile defense agency called for accelerated production of the latest generation of Patriot interceptor missiles, called PAC-3.

The PAC-3 missile is designed to intercept and destroy cruise and ballistic missiles with ranges of up to 1,000 kilometers (600 miles).

But the Pentagon only has 40 of the missiles in stock, which means it will have to rely on less capable Patriot-2 missiles to protect US forces from possible Iraqi Scud missile attack.