How America is helping to whitewash Cambodia's crimes against humanity.

Yesterday, in Cambodia, a perpetrator of one of the twentieth century’s great crimes was sentenced. Kang Kek Lew, also known as Comrade Deuch, was the head of the infamous Tuol Sleng prison during the reign of the Khmer Rouge, and was at least partly responsible for the murder of more than 12,000 people. Now he will serve 19 years in jail.

But, after the West spent nearly a hundred million dollars to create a tribunal in Cambodia, this is all we have to show for it, at least so far: a solitary conviction of a man who was involved in less than one percent of the 1.5 to 2 million murders that took place in the country from 1975 to 1978. No one knows for sure if the next phase of the tribunal—the trial of the four highest ranking Khmer Rouge leaders still alive—will occur in 2011, 2012, or even at all. Some of the accused are elderly and frail, and may die before their trial begins, as another arrested leader, Ta Mok, did in 2006.

Even if the other trials do go forward, it will be difficult to argue that justice has been served. Authority at the tribunal is divided between international and Cambodian officials, and the two sides cannot agree on how many people to prosecute. International prosecutors want to charge at least five more individuals for their role in the mass killings. But Cambodia’s current leader, Hun Sen, has said that he does not want any more trials, and the Cambodian team has argued against further indictments. Moreover, even if those additional trials were to take place, it would still leave the vast majority of the guilty unpunished. It took more than ten people to murder up to 2 million Cambodians. It is now certain that none of the thousands of lower-level murderers will ever stand trial.

How did the matter of justice in Cambodia go so badly awry? The answer begins with the fact that the current Cambodian regime is riddled with former members of the Khmer Rouge. But part of the fault also lies with the United States.

In December 1978, Vietnam, reacting to unprovoked attacks on its own territory and civilians, invaded Cambodia and deposed the Khmer Rouge regime headed by Pol Pot. The invaders installed a puppet regime that was staffed at the highest levels by former mid-level Khmer Rouge political and military cadres. The cadres had fled Cambodia to Vietnam not out of revulsion at the holocaust, but out of fear of Pol Pot’s executioners who were conducting purges. The new regime was led first by Heng Samrin and later by Hun Sen.

The Heng Samrin-Hun Sen government was obviously a substantial improvement over the Khmer Rouge, but it was still a brutal authoritarian regime. For the next 30 years, it would murder its political opponents and preside over a politicized and corrupt judiciary. It would open Cambodia to various criminal syndicates, including drug traffickers, human traffickers, and illegal loggers. And even after the Vietnamese ended their occupation of Cambodia in 1989, and Soviet aid dried up, the government would find ways to cling to power.

In 1991, Hun Sen reluctantly accepted a U.N. plan to occupy the country and pave the way for elections. Unfortunately, the United Nations was not prepared to use its 22,000-strong military and police contingents to enforce its written mandate. Discerning this, Hun Sen’s army and Pol Pot’s guerrillas refused to disarm. The non-communists won the May 1993 elections, despite the campaign of terror waged by both Hun Sen and Pol Pot. But the heavily armed Hun Sen was able to bully his way into an ostensible coalition government with the unarmed election winners—the non-communists, led by Prince Norodom Ranariddh. Four years later, Hun Sen ousted Ranariddh in a bloody coup, in which more than 100 non-communist political leaders and military officials were murdered.

Meanwhile, the Clinton State Department, at least at first, pursued a policy of engagement with Hun Sen, whose son was invited to attend West Point. Stability was the watchword of this policy. Following the 1997 coup, Clinton did impose a ten-year ban on U.S. government aid to Cambodia. But the Bush administration allowed the aid ban to lapse in 2007, and, more broadly, revived the policy of engagement. At one point, the administration invited then-Chief of National Police Hok Lundy—a known torturer, murderer, and human trafficker—to Washington to become a partner in the war on terror.

Hovering over Cambodian politics during all this time was the question of whether, and how, to prosecute the leaders of the Khmer Rouge holocaust. For two decades after taking power, the government did call for prosecution of Pol Pot’s circle. Yet it was noteworthy that the proposed targets of these prosecutions never included members of the new regime. For Hun Sen, the purpose of the tribunals was not justice; it was to delegitimize his armed opponents who were still holding out in remote rural areas.

In June 1997, Hun Sen and Ranariddh had signed a letter requesting U.N. assistance to establish a tribunal. And, even after ousting Ranariddh in a coup, Hun Sen continued to agree to a dominant role for the United Nations in the proposed tribunal. Meanwhile, a committee appointed by the U.N. Secretary General, noting Cambodia’s lack of a technically competent and politically independent judiciary, recommended that the tribunal be held in a foreign country and staffed by international judges and prosecutors.

By late 1998, however, Hun Sen had flipped his position. What had changed was Cambodian politics. During the mid-’90s, many of Pol Pot’s political and military commanders had defected with their units to the government side, where they were given a chance to share in the spoils of power. By 1997, the Pol Pot-led rump had begun to disintegrate in internal disputes. “Brother Number One,” Pol Pot, died in July 1998. When “Brother Number Two,” Nuon Chea, as well as the nominal president of the former regime, Khieu Samphan, defected in December 1998, the armed opposition to Hun Sen’s regime was finished. Suddenly, Hun Sen announced that it was time to “dig a hole and bury the past.” Within a matter of weeks, he told the United Nations that he no longer needed its help, and that any tribunal would be held in Cambodia under the country’s judicial processes.

In the end, the United States and the United Nations mostly backed down. They accepted Hun Sen’s demand that the tribunal be held in Cambodia. And John Kerry—whose interest in southeast Asian issues dated to his days as an antiwar activist—proposed a compromise under which a majority of judges would be Cambodian (though the international judges would have veto power should the Cambodians try to block indictments).

In theory, it might have worked, but in practice it has turned out to be disastrous. Hun Sen, whose government contains many former Khmer Rouge functionaries, remains reluctant to see many people put on trial. And because the trials are being conducted in Cambodia, with such heavy involvement by people who are appointed by Hun Sen’s government, it appears that he might just get his way.

No U.S. security interest is at stake in the events in Cambodia. The question of justice for this poor and ravaged nation remains significant only as a moral issue. Yet, perhaps because engagement, even with nasty regimes, has long been the default operating principle of the State Department, both the Clinton and Bush administrations were frequently content to cater to Hun Sen. Given that Barack Obama is preoccupied with so many other pressing issues, it seems unlikely that the United States—which is still helping to fund the tribunal—will reverse course anytime soon. And so, more than three decades after the end of the Cambodian killings, it is possible that yesterday’s sentencing of a sole murderer is all that the Khmer Rouge’s victims are going to get in the way of justice.

Stephen Morris is a senior fellow at the Johns Hopkins School of Advanced International Studies and author of Why Vietnam Invaded Cambodia.