KABUL - Warlords helped drive the Russians from Afghanistan, then shelled Kabul into ruins in a bloody civil war after the Soviets left.

"Chairman Karzai, I reaffirm to you today that the United States will continue to be a friend to the Afghan people in all the challenges that lie ahead," said then-President Bush in his remarks during a joint press conference. (White House photo by Paul Morse, 28 January 2002) Now they are back in positions of power, in part because the U.S. relied on them in 2001 to help oust the Taliban after the Sept. 11 attacks. President Hamid Karzai later reached out to them to shore up his own power base as America turned its attention to Iraq after the Taliban's rout.

With the Taliban resurging, the entrenched power of the warlords is complicating Karzai's promises to rid his new government of corruption and cronies, steps seen as critical to building support among Afghans against the insurgents.

"You can't build a new political system with old politicians accused of war crimes," said lawmaker Ramazan Bashardost, who finished third in the country's fraud-marred August election. "You can't have peace with warlords in control."

Two of Karzai's vice presidents - Mohammed Qasim Fahim and Karim Khalili - are ex-warlords. His outgoing military adviser, Abdul Rashid Dostum, has been accused of overseeing the suffocation deaths of up to 2,000 Taliban prisoners during the 2001 U.S.-led invasion.

The term warlord is applied to the commanders of the Afghan resistance who fell out with each other after the defeat of the Soviets. They see themselves as political figures and patriots who defend their people in areas of the country where the central government has little or no control. They often refer to themselves as "mujahadeen," which means holy warriors.

Karzai sought support from those branded as warlords to bolster his weak power base, win re-election and build alliances with ethnic groups. He has defended those ties publicly, pointing out that the U.S. backed the same people eight years ago when it engineered the war to oust the Taliban and brought Karzai to power.

But the U.S. and its allies fear that the continued strength of the warlords undermines government authority. It is hard to convince ordinary Afghans to obey the laws, pay their taxes and support the government when it is dominated by men who flounted the rules to amass power and fortunes.

International pressure is mounting on Karzai to rid his government of corruption and sideline the warlords. Leaders of the U.S., Britain and other troop-contributing countries cannot ask their own soldiers to risk their lives for a corrupt government.

"I am not prepared to put the lives of British men and women in harm's way for a government that does not stand up against corruption," Prime Minister Gordon Brown said Friday.

Last week, Kai Eide, the U.N. mission chief in Afghanistan, suggested time was running out. "We can't afford any longer a situation where warlords and power brokers play their own games," he said. "We have to have ... significant reform."

And Obama told the Afghan leader last week that assurances of reform had to be backed up with action.

Presidential spokesman Humayun Hamidzada defended Karzai, saying he has appointed to government posts Afghans from all walks of life and from all political backgrounds. He said "the path of inclusivity" was crucial for stability.

A nationwide survey by the Afghan Independent Human Rights Commission, however, found 76 percent of the 4,151 polled believed security would improve if war criminals were brought to justice. Only 8 percent felt it would decrease security and 13 percent said they did not know. The remaining 3 percent were missing.

Removing them from government is "by far the most important issue facing the country today," said Brad Adams, the Asia director of Human Rights Watch.

The New York-based rights group has called for several senior officials in Karzai's administration to be tried for war crimes alongside some of Washington's biggest enemies, like Taliban leader Mullah Omar and insurgent chief Gulbuddin Hekmatyar.

Faction leaders defend their roles in the civil war of the 1990s, which broke out when the pro-Soviet government collapsed following the departure of Moscow's troops. Some of them held out against the Taliban after the Islamist movement seized Kabul in 1996. The Bush administration supported them in the 2001 attack against the Taliban, enabling the U.S. to oust the Islamists from power without committing large numbers of U.S. ground troops.

But some of the alleged crimes attributed to the warlords were so odious that Washington could not ignore them. Witnesses claim Dostum's forces placed Taliban prisoners in sealed cargo containers and suffocated them to death before burying them en masse, according to a State Department report. Dostum denies involvement in the deaths.

The U.S. and its allies pressured Karzai into firing Fahim, his new vice president, as defense minister and dropping him from the ticket in the 2004 election. He tapped him again as his running-mate this year, a move that helped split the opposition vote.

All that has encouraged a climate of impunity that has trickled down through Afghan society. Rights groups accuse soldiers and police loyal to warlords of kidnapping, extortion, robbery and the rape of women, girls and boys.

In the countryside, local commanders "run their own fiefdoms with illegal militias, intimidate people into paying them taxes, extract bribes, steal land, trade drugs," said John Dempsey of the U.S. Institute of Peace. "They essentially rule with impunity and no government official, no judge, no policeman can stand up to them."

Karzai has tried to rein in warlords before, dispatching his finance minister to haul back sacks of cash from governors reluctant to pay tax to the central government.

But removing strongmen from power or putting them on trial is risky: it could inflame ethnic tensions and alienate regional commanders whose support both Kabul and Washington need to contain the burgeoning insurgency.

A September report released by New York University's Center on International Cooperation said the NATO-led coalition is fueling the problem by relying on militias loyal to local commanders - some involved in rights abuses and drug trafficking - in an effort to bolster security.

The war plan advanced by America's top Afghanistan commander, Gen. Stanley McChrystal, mentions "regional power brokers" with "loyal armed followers," but does not advocate removing them. The U.S. used local armed groups in Iraq to fight al-Qaida and similar militias in Afghanistan have been successful in providing intelligence about the Taliban.

Karzai has been pressured to take action before. In 2005, he was pushed to approve a reconciliation and justice plan that included a vetting system to keep grave rights abusers out of government. But almost none of it was implemented, Dempsey said. Even building a monument or declaring a holiday for war victims was deemed too controversial because Afghanistan and its international backers feared examining the past too closely could destabilize the fragile government.

Sima Samar, chairwoman of the country's human rights commission, said warlords do not necessarily have to be tried. They could face truth commissions, or start by simply apologizing.

There is a lack of political will in bringing them to justice, she said. "We will never have sustainable peace until we tackle our past."

Another presidential spokesman, Hamed Elmi, said commanders like Fahim should be praised. They "played a vital role defending our country against the Soviet occupation and the Taliban. And for the last eight years, they've supported the U.S. in the war on terror."

He said Afghanistan's criminal justice system is ready to try anyone for rights abuses, "but so far, we've seen no proof they've done anything wrong."

Human Rights Watch has documented the indiscriminate killing of civilians by militias loyal to both Fahim and Khalili during the 1990s, which it says constitute war crimes. The group interviewed scores of witnesses accusing militias of murder, pillage and the abduction of ethnic rivals in violation of international humanitarian law.

Akbar Bai, a leader of the country's Turkmen minority - who Dostum beat and briefly kidnapped last year after storming his Kabul home with 100 armed fighters - said the U.S. and its Afghan allies are "fighting the wrong war."

"Karzai's No. 1 problem is the warlords," said Bai, who was released only after government troops surrounded Dostum's mansion. "If you don't remove these people from power, you'll never see peace in Afghanistan."