With the Pentagon now rushing thousands of troops from Texas to the Persian Gulf, a number of seasoned Gulf War ground commanders said yesterday that the U.S. invasion force moving rapidly to Baghdad is too small and should have included at least one additional heavy Army division.

"In my judgment, there should have been a minimum of two heavy divisions and an armored cavalry regiment on the ground -- that's how our doctrine reads," said retired Army Gen. Barry R. McCaffrey, who commanded the 24th Mechanized Infantry Division during the 1991 Gulf War.

McCaffrey's comments are part of a heated debate underway among current and former ground commanders and strategists about a war plan built upon the concept of a "rolling start" -- in which combat actions begin before the arrival of all ready forces, which are then brought forward or held back, depending on how the battle proceeds.

The 21,000 soldiers of the 4th Infantry Division, based at Fort Hood, Tex., could begin arriving at staging areas in Kuwait almost immediately. But the 35 cargo ships laden with the division's heavy armor and equipment will not complete their journey from the Mediterranean, through the Suez Canal and Red Sea, and begin arriving in Kuwait until the first week of April at the earliest, defense officials said yesterday.

Those ships had been waiting for weeks off the coast of Turkey to unload, as the original war plan called for the 4th to set up a base there and open a northern front. From there, the division was to advance on Tikrit, Iraqi President Saddam Hussein's hometown, and Baghdad, thereby forcing the Iraqi military to defend its capital from two directions.

That plan was abandoned after Turkey's parliament refused to allow U.S. forces to launch from Turkish soil. President Bush then ordered the invasion to begin last week with only one heavy division, the 3rd Infantry in Kuwait, on the ground, forgoing the second heavy division that McCaffrey and others have thought critical to beginning the war with a massive blow.

How large a force is necessary to invade Iraq has been a point of contention for months between some ground commanders, particularly those in the Army, and Defense Secretary Donald H. Rumsfeld. He insisted that air power, information dominance and speed enable the U.S. military to achieve much greater effect with a smaller, more agile force.

The loss of the 4th Infantry Division from the original invasion force did not alter Rumsfeld's calculus. He and others cautioned against waiting for the division to arrive in Kuwait before invading, with hot summer weather approaching in the Iraqi desert and delay seen as affording Hussein more time to prepare.

"It is my position that we would be much better off if we had another heavy division on the ground, and an armored cavalry regiment to deal with this mission in the rear," said retired Army Lt. Gen. Thomas G. Rhame, who commanded the 1st Infantry Division during the Gulf War. "It's not serious, but life would be a lot simpler if the secretary had another front open, which he was denied."

Army Maj. Gen. Stanley McChrystal, vice chief of operations for the Joint Chiefs of Staff, told reporters at the Pentagon yesterday that he does not believe the U.S. invasion force is too small and too light.

Army Gen. Tommy R. Franks, commander of the war in Iraq, has "incredible flexibility," McChrystal said, with the heavy 3rd Infantry Division pushing rapidly to Baghdad supported by the 101st Airborne Division, the 1st Marine Expeditionary Force and a British division.

Retired Marine Lt. Gen. Paul Van Riper, now a Pentagon consultant, agreed with that assessment. He said those units -- all of which have been reinforced with additional troops and equipment -- represent "more combat power on the ground than is generally recognized."

One Army officer who was involved in some aspects of the war plan said air power more than offsets the firepower that would have been provided by the Abrams tanks, Bradley Fighting Vehicles, artillery and multiple-launch rocket systems of the 4th Infantry Division.

"Air power roams at will over the battlefield and can cope with any significant threat [that] concentrates to disrupt the rear," the officer said, adding that Iraqi Republican Guard divisions are "incapable of any resistance other than static defense."

He also contended that the Iraqi military never successfully attacked the U.S. flanks and will not be able to do so now.

But McCaffrey said that long, unprotected supply lines reaching from Kuwait all the way to Baghdad have been shown to be vulnerable. The ambush of an Army maintenance convoy Sunday resulted in seven deaths and five U.S. prisoners of war.

Army doctrine, he said, calls for armored cavalry regiments to patrol the flanks of the advancing force and protect the terrain it has traversed. Military police battalions, he said, are typically used to patrol bridges and intersections to be controlled by military police battalions.

Such forces have received deployment orders, he added, but they are still back in the United States, waiting to get into the fight. As for the adequacy of air power, McCaffrey said it cannot substitute for the powerful combination of M1 Abrams tanks, Bradley Fighting Vehicles and AH-64D Apache Longbow helicopter gunships when it comes to a confrontation with Republican Guard divisions, particularly when they are dispersed.

"When you package it the right way, the Bradley-Abrams-artillery-Apache team [enables the U.S.] to stand up to enormous combat pressure and not lose many troops," McCaffrey said.

His fear at this point, he added, is that waiting for reinforcements for a final attack on Baghdad could give the Iraqis time to recover. "You don't get up there and let them get their nerve back," McCaffrey said. "You got to go in there and bust their chops badly, and let the speed and momentum and violence overwhelm them."

Retired Army Maj. Gen. William L. Nash, a commander in the Gulf War, agreed that another heavy division on the ground would be highly desirable.

"The stability of the liberated areas is clearly as issue," he said. "The postwar transition has to begin immediately in the wake of the attacking forces, and they seem to be short of forces for those important missions at this time."

Maj. Gen. Stanley McChrystal, vice chief of operations for the Joint Chiefs of Staff, said the invasion force sent into Iraq is not too small or light. McChrystal said the U.S. commander of the war has "incredible flexibility."