MEDIA REPORTS about the alleged massacre of 24 civilians by U.S. Marines in Haditha, Iraq, have focused on the idea that soldiers "snapped" under combat stress. But as details emerge about Haditha and other civilian killings, including allegations of cover-up attempts -there is increasing concern that U.S. military forces could be turning rogue because some members think they operate in a culture of impunity. As Iraqi Prime Minister Nuri al-Maliki told The Guardian, of London, on June 3, killings of civilians have become "a daily phenomenon." "They crush them with their vehicles and kill them just on suspicion," al-Maliki said.

Last Monday, the U.S. military announced that three members of the 101st Airborne Division had been charged with murder and obstruction of justice in the May 9 shooting deaths of three Iraqi prisoners. According to CNN, they allegedly threatened a fellow soldier who witnessed the shootings, telling him they would kill him if he talked.

As investigations progress into this case, Haditha, and other alleged killings, such as that of a pregnant Iraqi woman and a disabled man, it is instructive to look to Colombia, where U.S.-trained and supported troops are also facing allegations of rampages outside the law.

Little attention has been paid internationally to a May 22 massacre in which a Colombian Army group killed 10 members of an elite counter-drug police unit. This police unit, trained by the U.S. Drug Enforcement Administration, had captured about 200 traffickers over the years. The killings were initially described as a case of friendly fire, but the Colombian Prosecutor General's Office recently charged that it was a massacre committed by members of the armed forces doing a "favor" for drug traffickers.

And the other week the United Nations High Commission for Human Rights asked the Colombian Attorney General's Office to investigate 37 cases of apparent extrajudicial killings. The armed forces presented the majority of the cases as guerrillas killed in combat during 2005-06, when really, according to the United Nations, the armed forces seem to be killing civilians and sometimes dressing the dead in rebel military uniforms to justify their deaths.

José Miguel Vivanco, director for the Americas of Human Rights Watch, who has closely followed the Colombian situation, told me last week that "Many units of Colombia's Armed Forces have a long history of human-rights abuses, as well as toleration [of], support [of], and even collusion with armed groups and drug traffickers." The office of the U.N. commission for human rights said that it was worried about allegations of mass arrests carried out by Colombian government forces without a legal basis, reports of torture and forced displacement, instances of rape by troops, and efforts to cover their tracks by tampering with evidence and intimidating witnesses.

The U.S.-backed Colombian government -- the only right-wing government in South America today -- has been pursuing a military buildup in the context of a 40-year-old war that pits two leftist rebel groups against right-wing paramilitary factions and government forces. But according to the U.S. State Department's annual report on human rights, released on March 8, "There continued to be credible reports that some members of the [Colombian] security forces cooperated with illegal paramilitaries. Such collaboration often facilitated unlawful killings and sometimes may have involved direct participation in paramilitary atrocities."

Considering such facts, it's surprising that on May 26 U.S. Secretary of State Condoleezza Rice "certified" to Congress that the Colombian government and armed forces were continuing to meet statutory criteria for fulfilling U.S. requirements related to human rights for receiving American assistance.

Vivanco, of Human Rights Watch, pointed out that despite strong evidence of human-rights abuses and collusion to commit crimes, the United States had repeatedly certified that Colombia's armed forces were meeting human-rights conditions on military assistance. "This time," he said, "the United States certified Colombia's compliance with the conditions without even mentioning the alarming reports of an increase in extra-judicial executions by the army, the army's killing of 10 anti-narcotics police officers, and serious allegations of torture in military training."

Is this approach to certification giving the Colombian armed forces the impression that they have a blank check, because no matter what they do the United States will always find a way to certify them?

Such horrors are being partly financed by the U.S. government and/or the U.S. taxpayers. According to Adam Isacson, of the Washington-based Center for International Policy, Colombia has received about $4.7 billion in U.S. aid since 2000 -- of which $3.8 billion has gone to the military and the police. The Bush administration has requested $760 million in U.S. aid to Colombia for fiscal year 2007. The U.S. House has requested even more aid for Colombia: about $800 million. This would be the largest single-year aid amount that Colombia had ever received.

Both President Bush and Colombian President Alvaro Uribe have suggested that killings of civilians by their respective armies are an aberration. The two men met June 14 at the White House, where Bush praised Uribe for his commitment to human rights. Uribe thanked Bush for his support, and pledged to do a better job of eradicating drugs. According to the White House transcript, Bush said: "I told President Uribe that one of the things I will do a better job of is communicating to the people of South America and Central America my country's desire to promote justice and education and health. We spend about $1.6 billion a year in Central and South America. I want the people to understand that money is meant to help them, to help improve their lives. I want the people to understand America is a considerate country, that we care about justice."

Let's hope that Bush and Uribe's vision of justice includes investigation of rogue actions by military personnel and strong punishment of those found guilty. The leaders of both countries will be judged by history whether their actions prevented more atrocities, or whether their inaction led to the deaths of innocents.

Maria Cristina Caballero, a Colombian journalist, is a fellow at the Center for Public Leadership at Harvard University's John F. Kennedy School of Government.