Eric Reeves is a professor at Smith College and the author of “Compromising with Evil: An Archival History of Greater Sudan, 2007-2012.”

The Darfur genocide in western Sudan — the first genocide of the 21st century and the longest one in more than a century — is about to achieve another distinction. It will be the first genocide in which the victims will be abandoned. An international peacekeeping force designed to halt violence against civilians and humanitarians — the United Nations-African Union Mission in Darfur, or UNAMID — is on the verge of being gutted or perhaps eliminated altogether.

This is despite the fact that some 3 million people have been internally displaced or turned into refugees; almost 500,000 were displaced last year alone. E stimates vary, but we must speak of several hundred thousands of deaths — perhaps half a million — from violence and its consequences, and mortality rates are rising. The victims come overwhelmingly from the non-Arab tribal groups that have been targeted from the beginning of Khartoum’s brutal counterinsurgency against rebel forces.

Although it’s been reported on only fitfully, planning for UNAMID’s diminished future is well underway. Among the planners? The génocidaires of the regime in Khartoum, who insist that the “exit strategy” — agreed to in principle by the U.N. Security Council in August — be executed as rapidly as possible. The force has already been cut by 10,000 and now stands at approximately 17,000 uniformed personnel. The regime wants 15,000 more gone this year.

Criticism of UNAMID is longstanding; indeed, it preceded deployment of the civilian-protection mission in January 2008. The mission was set up to fail, largely because Khartoum was given excessive control over the deployment of personnel and equipment. This led to poor troop quality, with the regime rejecting many highly qualified peacekeeping contributions (such as a Swedish-Norwegian engineering battalion). Essential weaponry and aircraft were also denied. Despite a status-of-forces agreement that was supposed to give UNAMID unrestricted access, Khartoum has systematically obstructed, delayed or compromised countless protection and monitoring missions.

As badly as UNAMID has performed, however, it is all that allows international humanitarian organizations to remain in Darfur. If UNAMID withdraws, or is hopelessly compromised, these organizations may be forced to end their work. To date, some 25 to 30 international relief organizations have been expelled by Khartoum or have withdrawn because of a lack of security. This has occurred against a backdrop of extreme malnutrition in many locations, a desperate lack of clean water and sanitation, and a rapidly collapsing system for providing primary medical care.

Decisions about reconfiguring UNAMID are being made at this very moment, and yet we hear nothing of significance from the Obama administration about the urgency of preserving key elements of the force. Yes, a facile international chorus has declared “Darfur won’t be abandoned,” but there are reasons to be skeptical. Leading this chorus is the expedient Hervé Ladsous, head of U.N. peacekeeping operations, who not so long ago argued that a drawdown of UNAMID was justified by improved security conditions, even as violence has escalated for three years.

Moreover, a brute geopolitical fact defines current planning. UNAMID must be reauthorized before June 30. But Khartoum has veto-wielding friends on the Security Council in the form of China and Russia; they are likely to support the regime, even in its most unreasonable demands. Russia is of particular concern, given President Vladi­mir Putin’s general hostility to any Western initiative. In a revealing show of perverse solidarity, Russia sided with Khartoum in rejecting a recent report by Human Rights Watch that documented the mass rape last fall of more than 220 girls and women by Khartoum’s army troops in the town of Tabit. The evidence in the report is so overwhelming that the Russian denial of its findings suggests an unwillingness to look at the reality in Darfur except through Khartoum’s eyes.

Depending on the character of the newly authorized force — assuming one is authorized at all — humanitarian organizations may be forced to withdraw from what is already a terribly insecure environment. The epidemic of sexual violence will continue to accelerate, with the Arab militias most responsible operating with total impunity. More than half of Darfur’s pre-war population of 6.5 million people needs assistance, and yet humanitarian capacity is shrinking. U.N. agencies such as the World Food Program cannot function without implementing partners, precisely the function that has been fulfilled by the organizations contemplating withdrawal. If they leave, the death toll could be catastrophic.

The United States, Britain and France need to muscle up politically in the Security Council now or the fate of Darfur will be dictated by the very men who began the genocide 12 years ago. This would be unprecedented in the grim history of genocide.