Last summer, after more than two years of terrible fighting, it looked as though the United States might finally have landed on a viable approach for ending the civil war in Sudan. Since the conflict began in April 2023, Sudan’s state has collapsed, and its people have suffered the world’s largest humanitarian crisis. The battle lines have moved back and forth across the country, devastating the capital, Khartoum, and a score of other cities. Today, Khartoum and places east of the river Nile are dominated by the Sudanese Armed Forces, led by General Abdel Fattah al-Burhan, while the western half of the country is largely controlled by the SAF’s enemy, the paramilitary Rapid Support Forces, led by General Mohamed Hamdan Dagalo, known as Hemedti.

In June, the Trump administration convened the “Quad”— Egypt, Saudi Arabia, the United Arab Emirates (UAE), and the United States—to discuss a pathway to peace. These countries are more than mediators: throughout the war, Egypt and Saudi Arabia have supported the SAF, while the Emiratis have backed the RSF, although they deny it. Since these regional powers have had an outsize role in the conflict, it was hoped that a strong Quad agreement could produce a lasting cease-fire.

Yet expectations that U.S. President Donald Trump might inject vigor into the Sudanese peace process have until now been unrealized. In September, the Quad announced a plan that involved a cease-fire, access for humanitarian aid, and political negotiations toward a civilian-led government. But a month later, as talks on implementing the plan stalled, the RSF carried out the worst atrocity of the entire war. After a brutal starvation siege that had lasted 18 months, RSF forces overran the city of El Fasher in the Darfur region. As they took the city, RSF fighters massacred at least 7,000 people, many of them civilians. As many as 100,000 people have yet to be accounted for, although some have trickled into towns and villages hundreds of miles away, their faces hollow as they struggle to find words to recount the horrors. Not only did the RSF fighters kill with impunity; they also circulated “trophy” videos of themselves torturing and murdering their victims with glee and denigrating them with dehumanizing epithets.

Despite international outrage, the fighting has not abated in the three months since. Currently, RSF forces are encircling the city of El Obeid in North Kordofan and have struck civilian targets, including a kindergarten. Meanwhile, both sides are continuing to receive weapons from their external backers. Since October, observers have noted an increase in military cargo flights to RSF-controlled airports, and the RSF has been deploying sophisticated Chinese-made drones, as well as Colombian mercenaries. Investigators have tracked the flights to the UAE. With the new supplies, RSF forces may even threaten Khartoum, which they mostly controlled earlier in the war before the SAF pushed them out. At the same time, Egypt and Turkey have been funneling more arms to the SAF.

The longer the fighting continues, the greater the risk that it becomes a regional conflagration. The war is already entangling Sudan’s African neighbors. The RSF’s supply lines run through Chad, Libya, Somalia, and South Sudan—and may yet involve Ethiopia and Kenya. Its constituency of recruits among rural populations, especially historically nomadic communities, stretches westward across Sahelian Africa. Since the fall of El Fasher, there have been reports of cattle-herding Arab groups crossing the borders from the Central African Republic and Chad, aiming to seize the newly vacated lands. And the Sudanese war is also intermeshed with the volatile situation between Eritrea and Ethiopia, which threatens to devolve into a major war of its own.

By convening the Quad, Washington has correctly recognized that the road to ending Sudan’s war runs through the Gulf. But what few have fully grasped is that the conflict itself is international in ways that are new and different from previous Sudanese conflicts. Today, the territorial nation-state in Sudan—and in many parts of Africa and the Middle East—is rapidly being eclipsed by borderless fiefdoms run by warlords who answer to foreign patrons with deep pockets. And that has made this war, despite its deep unpopularity among the Sudanese themselves and the misery and hardship it has brought to tens of millions of people, much harder to contain. Without more decisive engagement from the highest levels of the Trump administration, there is now a serious risk that Sudan’s war tips the Horn of Africa, the Nile Valley, and the Sahara-Sahel region into a vast arena of anarchy.

Resolving the war in Sudan would be difficult even under conducive circumstances. The El Fasher massacre in October captivated world attention for its exceptional brutality, but it was only the most conspicuous in a pattern of atrocities that has scarred the entire country since the fighting erupted. What happened in El Fasher echoed the killings in West Darfur that marked the early months of the war—killings that the U.S. State Department labeled a genocide. The takeover of the Darfuri........

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