The sea of oil under Iraq is supposed to rebuild the nation and then make it prosper. But at least one-third, and possibly much more, of the fuel from Iraq's refineries is diverted to the black market, according to U.S. military officials. Tankers are hijacked, drivers are bribed, papers are forged and meters are manipulated -- and some of the earnings go to insurgents who are still killing more than 100 Iraqis a week.

"It's the money pit of the insurgency," said Capt. Joe Da Silva, who commands several platoons stationed at the refinery.

Five years after the war in Iraq began, the insurgency remains a lethal force. The steady flow of cash is one reason, even as the buildup of U.S. troops and the recruitment of former insurgents to American-backed militias have helped push the number of attacks down to 2005 levels.

In fact, money, far more than jihadist ideology, is a crucial motivation for a majority of Sunni insurgents, according to U.S. officers in some Sunni provinces and other military officials in Iraq who have reviewed detainee surveys and other intelligence on the insurgency.

WHO ARE THESE GUYS?

The suicide bombers who have killed 10,000 people in Iraq, including hundreds of U.S. troops, usually are alienated young men from large families who are desperate to stand out from the crowd and make their mark, according to a U.S. military study.

As long suspected, most come from outside Iraq. Saudi Arabia, home of most of the Sept. 11 hijackers, is the single largest source. And the pipeline is continually replenished by Al-Qaida in Iraq's recruiters.

The study, obtained by the Associated Press, profiles the suicide bombers and their support system based in part on interrogations of 48 foreign fighters who were captured or surrendered. Most are Sunni Muslim men from 18 to 30, with the mean age of 22. They are almost always single males with no children, and they tend to be students or hold blue-collar jobs.

The majority have six to 12 years of schooling, and most come from families in the poor or middle-classes and have six to eight siblings.

"In these large family groups, individuals seek ways to 'make their mark,' to set them apart. In many ways, entering jihad gives sons a way to show themselves unique in a large family," the summary said.

According to the National Counterterrorism Center in Washington, 949 suicide bombers killed 10,119 people and wounded 22,995 from the beginning of 2004 until now.

VENTING THEIR ANGER

In Minneapolis on Saturday Meredith Aby, a member of the local Anti-War Committee, told an anti-war rally in Loring Park that a majority of American citizens want the war over.

"People need to get out in the streets and demand change. Just saying the war is unpopular is not enough," Aby said. "People should think more critically how this government beats the drums for war."

Instead, protesters banged their own drums as they marched and shouted phrases -- including, "[President] Bush lies, thousands die, troops home now" -- from Uptown to Loring Park.

Traffic along Hennepin Avenue slowed occasionally as numerous passing vehicles honked in support.

UNFINISHED BUSINESS

The United Nations on Saturday called on the Iraqi government and the United States to take advantage of a period of reduced attacks to address the human-rights problems that plague Iraq, including violence against civilians, abuse of detainees, persecution of women and ethnic minorities, and a lack of food and shelter for displaced people.

The U.N. Assistance Mission for Iraq applauded Baghdad's decision to ratify the U.N. convention against torture and the government's efforts to alleviate overcrowding in prisons, and it took note of new judicial safeguards for detainees.

Among the concerns cited in the report were an increase in the number of juveniles held in detention, the so-called honor killings of women by family members in the northern region of Kurdistan, the killing of civilians by private security contractors and "continuing reports of the widespread and routine torture or ill treatment of detainees, particularly those being held in pretrial detention facilities."

STAFF WRITER TERRY COLLINS AND NEWS SERVICES