U.S. military forces in the Persian Gulf region are prepared now for a war against Iraq but could wait for months at a high state of readiness if necessary, the military's top officer said Wednesday.

"We're ready now. The Iraqi regime should have no doubt," said Gen. Richard Myers, chairman of the Joint Chiefs of Staff.

Some have questioned how long the tens of thousands of U.S. forces now assembling in the Gulf region could keep their edge if President Bush decided to give diplomacy more time to persuade Iraq to disarm, as several U.S. allies and some in Congress are urging.

Myers said the troops could stay ready for several months if necessary. The Pentagon could rotate fresh forces in to replace those who arrived first, if that were needed to maintain their fighting edge, he said.

The Pentagon, meanwhile, reported that more than 20,000 additional members of the National Guard and Reserve were called to active duty over the past week, pushing the total number mobilized to 78,906 as of Wednesday.

Myers expressed satisfaction with the pace of the U.S. troop buildup but would not discuss specifics.

The Navy said Monday it is doubling the number of aircraft carrier battle groups within striking distance of Iraq, and aides to Defense Secretary Donald H. Rumsfeld said he is contemplating sending still more troops.

Gen. Tommy Franks, the Central Command commander who would run a war against Iraq, was departing his Tampa, Fla., headquarters Tuesday night for a weeklong visit to the Persian Gulf region, officials said. Details of his trip were being withheld for security reasons. He was last in the Gulf in December, when he oversaw a computerized war game staged from his new command post near Doha, Qatar.

The USS Constellation battle group already is operating in the northern Persian Gulf and the USS Harry S. Truman is in the Mediterranean. They will be joined by the USS Abraham Lincoln, originally scheduled to return this month to its home port at Everett, Wash., and the Norfolk, Va.-based USS Theodore Roosevelt, which is undergoing training exercises off the coast of Puerto Rico in preparation for deployment.

The Lincoln has been in port at Perth, Australia, for repairs but departed Monday after receiving its new deployment order, said Lt. Cmdr. Jeff Bender, a public affairs officer aboard the carrier. The Lincoln had been operating in the Gulf and was headed home when it was told to hold up in Australia pending new instructions.

Officials said Tuesday that Rumsfeld is considering other deployments, including the possible dispatch of still more carrier battle groups to the Gulf region. The USS Kitty Hawk, for example, may go from its home port in Japan, and the Bremerton, Wash.-based USS Carl Vinson could replace the Kitty Hawk in the Pacific.

Also available for near-term tours in the Gulf region are the USS Nimitz in San Diego and the USS George Washington in Norfolk, Va.

Each carrier has an air wing comprising 70-80 aircraft, including F/A-18 Hornet and F-14 Tomcat fighters, as well as surveillance, electronic warfare, search-and-rescue and command-and-control aircraft. A battle group also includes surface ships capable of firing Tomahawk cruise missiles and at least one submarine.

The additional naval air power is part of a broader buildup of U.S. forces in the Persian Gulf region. More than 60,000 troops are already there, to be joined by about 120,000 more over the next few weeks. When the buildup is finished, before the end of February, President Bush will have the option of attacking Iraq from multiple directions.

The Army, meanwhile, continued its surge of equipment and soldiers to the Gulf area.

The 4th Infantry Division, equipped with tanks, attack helicopters and artillery to defeat armored forces, is heading a group of 37,000 soldiers ordered to reposition in the Persian Gulf region. Their equipment will be shipped first, with the soldiers to go when final basing arrangements are worked out, officials said.

That division, based at Fort Hood, Texas, is considered the Army's most lethal and modern heavy division.

In addition to about 12,500 soldiers from the 4th Infantry at Fort Hood, nearly 4,000 soldiers from the division's 3rd Brigade at Fort Carson, Colo., and more than 20,000 troops from 10 other installations comprise the task force, said Fort Hood spokesman Cecil Green.

Green said he could not provide more details, such as where the soldiers will be based or when they will ship out.

Officials in Washington said it was possible that parts or all of the task force would go to Turkey. The Pentagon has wanted to put ground forces into Turkey to establish an option of invading Iraq from the north. Thousands of U.S. forces are already in Kuwait, training for a possible attack on Iraq from the south.

The Turkish government had resisted the U.S. request for base access for ground forces, but U.S. officials said Tuesday an agreement was in the works to allow roughly 20,000 to be based there. The European Command already flies flight-interdiction missions over northern Iraq from Turkey.