ABOARD THE USS NASSAU IN THE NORTHERN PERSIAN GULF (AP) _ The 60,000 to 80,000 Iraqi troops defending against a possible Marine amphibious landing in Kuwait have not been targeted by the heavy allied bombing, increasing the risks associated with a beach assault, U.S. officers say.

The five or six Iraqi divisions deployed along the Kuwati shoreline were not subjected to the bombing directed at major Iraqi ground deployments elsewhere because the allies are trying to limit damage to residential and civilian areas of Kuwait, the officers said.

''The Kuwaitis who are advising us just don't want us going in there and dropping bombs in an indiscriminate manner,'' said Navy Cmdr. Rich Barkell, intelligence officer for the landing force.

Naval minesweeping operations, intensified after two ships suffered significant damage earlier this week, were moving closer to the Kuwaiti beaches to clear paths for a possible Marine landing, authorities said.

The Marines continued preparations for such a landing, sending AV-8 Harrier jets to attack selected Iraqi positions in Kuwait, conducting night helicopter exercises, and setting up imaginary beaches at sea to run drills using landing craft that employ hovercraft technology and likely would be used to carry ashore the first waves of an assault force.

In a series of briefings Friday about the Nassau, the command ship for the 17,000-man Marine landing force, officers said targets for the Harriers and other allied aircraft helping prepare for a possible landing included coastal- deployed guns and defensive fortifications on the islands of Faylakah and Bubiyan, which could be used to fire at Marines attempting to land on the beaches of northern Kuwait.

They said Iraq has about 3,500 troops on Faylakah, but did not provide an estimate of troop strength on Bubiyan.

The officers said Saddam Hussein was having an increasingly difficult time resupplying his forces on those islands because of naval and air targeting of the small amphibious vessels used for supply runs.

The allies are using smart bombs and other methods to prepare several areas of the Kuwaiti shoreline for a landing, ''but it's very difficult to do that when you have to worry about civilian casualties,'' Barkell said. ''We can't go in with B-52 strikes along the coastline.''

If a landing is ordered, the allies would have no choice but to pound residential areas in the planned landing area with bombs and naval gunfire to provide cover for the Marines and take out tanks and artillery guns aimed at the shoreline, he said.

The officers said the allies had ways of alerting Kuwaiti civilians of impending strikes, but declined to be specific.

The 30-odd ship amphibious force is spread throughout the Persian Gulf, with the Nassau forward so its Harriers can easily reach targets in Kuwait.

The Iraqis have not flown a combat mission in nearly two weeks and their navy is all but destroyed, but the officers said they worried nonetheless about the prospect of being attacked by Exocet missiles.

The commander of the Marines, Maj. Gen. Harry Jenkins, said in an interview Thursday that the U.S. command's concern for keeping U.S. casualties to a minimum was a large factor in his planning.

Contingency plans for amphibious operations have changed repeatedly during operations Desert Shield and Desert Storm, said Marine Col. Bob Mauskapf, operations officer for the landing force.

The options ranged from a full-scale beach landing involving landing craft and helicopters to operations as small as battalion and company-sized raids, Mauskapf said.

He said that sending some of the floating force ashore to support Marines now deployed in the northeast Saudi desert was another option.

The Navy operations officer from the amphibious group, Lt. Cmdr. Doug Mitchell, said ''everything is still on the table'' as an amphibious assault is weighed, but that the success of allied minesweeping might affect the planning.

Minesweepers now are clearing areas close to the Kuwait coast, he said, declining to be more specific because of operational concerns.

The sweeping intensified after two naval vessels, the USS Tripoli and the USS Princeton, struck mines earlier this week, Mitchell said.

Those vessels were some 60 miles to 80 miles offshore of Kuwait, but minesweepers had subsequently ''found a whole scrunch of mines in the area,'' he said.

Barkell said 180 mines have been spotted in the gulf since the war began, with more than 100 of the sightings confirmed.

The bulk of the mines are Iraqi replicas of World War I-vintage spiked Soviet mines, but also include high-tech sensor devices Iraq purchased from the French, Italians and Soviets, Barkell said.

''They're going to be clearing those mines for years,'' Mitchell said. Because of the heavy mine-laying in the offshore area, he said, ''you have to assume it's going to get thicker'' as minesweepers move closer to Kuwait.

Heavy mine concentrations in coastal areas could impact plans for the amphibious force, Mitchell said.

''As you can well imagine, it's like waking up to three feet of snow,'' he said. ''You'd be a little late for work if you had to dig out of all that stuff.''