DHAHRAN, SAUDI ARABIA, SEPT. 22 -- Top U.S. Army and Marine Corps officers have drafted contingency plans to mount ground assaults against Iraq from as many as four directions in complex combat operations that would require U.S. troops to cross the Jordanian desert and Turkish mountains to get to the Iraqi frontier, according to military officials.

The purpose of these multiple assaults, the officials said, would be to prevent Iraqi President Saddam Hussein from massing all 140,000 members of his elite Republican Guard against a U.S. invasion force that might be called upon to attack Iraqi occupation troops in Kuwait.

U.S. intelligence officials rate the Republican Guard troops, instrumental in Iraq's military victories over Iran in 1988, as comparable in training and motivation to U.S. combat troops.

The contingency plans for a multi-front war against Iraq are part of the military options being prepared for President Bush in the event a United Nations trade embargo fails to dislodge Iraq from Kuwait and the administration decides to pursue a military option. The plans suggest that while the announced U.S. role in the region is the defense of Saudi Arabia, there is also detailed preparation underway for large-scale ground offensives against Iraq and occupied Kuwait should that become necessary.

Among the most sensitive aspects of this planning is the requirement that the Bush administration secure attack corridors through Turkey and Jordan to open western and northern fronts against the Iraqi army and dilute the combat power of its formidable ground forces.

The opening of these fronts would take pressure off any landing by 11,000 U.S. Marines now afloat in amphibious assault ships outside the Persian Gulf and armored assaults by U.S. Army and multinational combat troops now in defensive positions in northeastern Saudi Arabia.

The Navy commander of the first Marine amphibious group to arrive in the area said Friday that in seizing Kuwait Iraq had taken more Persian Gulf coastline than it could adequately defend. And the Marine commander of the task force, Maj. Gen. Henry W. Jenkins, added, "They don't really know where we are, so we have the element of surprise -- we can pick and choose . . . an area and a time of our choosing."

Although 29,000 Marines have landed in Saudi Arabia, the Marines in the amphibious groups offshore will remain afloat to be available for the "forcible entry" mission they have trained for, officials have said.

One senior U.S. military official said two additional amphibious task forces, each carrying a Marine Expeditionary Brigade of 16,000 Marines, have been designated for deployment in the Mediterranean near Turkey and the northern Red Sea near Jordan should the offensive plan be activated. As many as three additional Army divisions also have been designated for deployment.

A U.S. strategy to open multiple fronts against Saddam is an attempt also to exploit the weaknesses of Iraq's military supply system, which built up during eight years of war with Iran a fixed and somewhat rigid system of roads, warehouses and transport along the 750-mile frontier with Iran.

"Their supply system is not geared to mobile operations or to project power," said one military analyst. Attacks from four sides would likely overwhelm such a system, which also would be under attack from U.S. and perhaps allied air power.

Military officials also point out that unlike the Vietnam conflict, where North Vietnam supplied its troops in the south under the cover of triple-canopy jungle and sanctuaries in Cambodia and China, Iraq has no cover for its ammunition depots, and its supply convoys will rumble across exposed desert roads to reach its troops.

Still, other analysts see options for a long Iraqi defense based on building up multilayered earthen defenses that U.S. and allied troops could not eliminate with air power alone and that would force close combat resulting in a significant number of casualties.

It could not be learned whether the Bush administration has broached the question of territorial access to either the Turkish or Jordanian governments. Turkey's President Turgut Ozal is due to visit Washington next week, when U.S. officials say they will have completed the outlines of financial aid packages for Turkey, Jordan and Egypt. Ozal has said that he would not allow Turkey to be a staging area for offensive military operations against Iraq.

The prospect of crossing Jordan's frontier would appear to pose special problems for Washington because Jordan's King Hussein has strongly opposed the deployment of U.S. forces in the region and continues a dialogue with the Iraqi leader. Jordan also has a well-regarded army.

Some military officials have expressed confidence, however, that the failure of the embargo to force an Iraqi withdrawal will not only build an international consensus for military action but will erode resistance in Ankara and Amman to providing access to Iraq for U.S. armed forces.

The Saudi government and the exiled government of Kuwait already are quietly urging the Bush administration to prepare for an offensive military campaign that could commence before the end of the year, but some senior U.S. military officials caution that building offensive ground combat power will require months of preparation after a presidential decision.

U.S. forces are far from numerical parity with the 360,000 Iraqi troops that the Pentagon estimates are primed for combat in Kuwait and southern Iraq. "If we were to go on the offensive, we would have to have a better ratio than we have," one military official said.