HUSAYBAH, Iraq – Extra body armor – the lack of which caused a political storm in America – has flooded into Iraq, but many Marines here promptly stuck it in lockers or under bunks. Too heavy and cumbersome, many say.

Marines already carry loads as heavy as 70 pounds when they patrol the dangerous streets in towns and villages in restive Anbar province. The new armor plates, while only about five pounds per set, are not worth carrying for the additional safety they are said to provide, some say.

“We have to climb over walls and go through windows,” said Sergeant Justin Shank of Greencastle, Pa. “I understand the more armor, the safer you are. But it makes you slower. People don’t understand that this is combat and people are going to die.”

Staff Sergeant Thomas Bain of Buffalo, N.Y., shared concerns about the extra pounds.

“Before you know it, they’re going to get us injured because we’re hauling too much weight and don’t have enough mobility to maneuver in a fight from house to house,” said Sergeant Bain, who is assigned to the 3rd Battalion, 6th Marine Regiment. “I think we’re starting to go overboard on the armor.”

Since the insurgency erupted in Iraq, the Pentagon has been criticized for supplying insufficient armor for Humvees and too few bulletproof vests. In one remarkable incident, soldiers publicly confronted Secretary of Defense Rumsfeld about the problem on live television.

Hometown groups across America have since raised money to send extra armor to troops, and the Pentagon, under congressional pressure, launched a program last October to reimburse troops who had purchased armor with their own money.

Soldiers and their parents spent hundreds, sometimes thousands of dollars, on armor until the Pentagon began issuing the new protective gear.

In Sergeant Bain’s platoon of about 35 men, Marines said only three or four wore the plates after commanders distributed them last month and told them that use was optional.

Top military officials, including Secretary of the Army Francis Harvey, acknowledge the concerns over weight and mobility but have urged that the new gear be mandatory.

“That’s going to add weight, of course,” said Mr. Harvey. “You’ve read where certain soldiers aren’t happy about that. But we think it’s in their best interest to do this.”

Marines have shown a special aversion to the new plates because they tend to patrol on foot, sometimes conducting two patrols each day that last several hours. They feel the extra weight.

In Euphrates River cities from Ramadi and Romanna, lance corporals to captains have complained about the added weight and lack of mobility. But some commanders have refused to listen. In the former insurgent stronghold of Fallujah, for example, commanders require use of the plates.

The Marine Corps has said a total of 28,000 sets of the plates, officially called small-arms protective inserts, or side SAPIs, will be in combat zones by April. The Army has said it is hoping to have 230,000 sets of plates in the field this year.