U.S. Marines have expanded their role in Sumatra's tsunami relief (search) operation after days of delays caused by Indonesian objections to armed U.S. troops and the setting up of a base camp on shore, officials said.

In a major compromise, the Marines agreed not to carry guns while on Indonesian soil and for the vast majority of troops to return to ships stationed off the coast after each day's operations.

Marines flew a French medical team to the shattered city of Calang by helicopter Wednesday and delivered supplies to Indonesian troops in Meulaboh, to the south. Navy crews based on the aircraft carrier USS Abraham Lincoln (search) have flown hundreds of relief missions in the past two weeks.

Like the Marines, the Navy crews carry no weapons and have no land base.

Intensive negotiations opened the way for expansion of helicopter relief operations and for the first batch of Marines to come ashore by hovercraft in Meulaboh on Monday.

"At first we were sent to known airfields," helicopter pilot Capt. David Shealy said Wednesday. "Now we are doing targets of opportunity, looking for small groups of people who are isolated and need help."

The Marines, diverted here from duty in Iraq (search), have scaled back their plans to send hundreds of troops ashore to build roads and clear rubble. Col. Tom Greenwood, commander of the 15th Marine Expeditionary Unit, said earlier this week that they would instead keep only a "minimal footprint," with most returning to their ship at night instead of establishing a camp ashore.

The bulk of the Marines' mission has become ferrying aid workers and transporting food from the amphibious assault ship USS Bonhomme Richard.

Hundreds of from troops from Australia, Singapore, Germany and other nations are also helping the relief mission. The Indonesian military is providing security for all of them.

Much of the devastation is in Aceh province, where separatist rebels have fought government forces for decades. Both sides say they won't fight during the tsunami emergency, although the military has warned aid workers that some regions are not safe.