Tensions have been brewing for weeks between Sudan's two most powerful generals, who just 18 months earlier jointly orchestrated a military coup to derail the nation's transition to democracy.
Over the weekend, those tensions between the armed forces chief, Gen. Abdel-Fattah Burhan, and the head of the Rapid Support Forces paramilitary group, Gen. Mohammed Hamdan Dagalo, erupted into an unprecedented battle for control of the resource-rich nation of more than 46 million people.
Both men, each with tens of thousands of troops deployed just in the capital of Khartoum, vowed not to negotiate or cease fire, despite mounting global diplomatic pressure. It is a deadly setback for a country at the crossroads of the Arab world and Africa, which four years ago ended the rule of a long-time dictator in part through largely peaceful popular protests.
Here's a look at how Sudan, a country with a long history of coups, reached this point and what is at stake.
WHAT PRECEDED THE FIGHTING?
In recent months, negotiations had been under way for a return to the democratic transition that had been halted by the October 2021 coup.
Under mounting international and regional pressure, the armed forces and the RSF signed a preliminary deal in December with pro-democracy and civilian groups. But the internationally brokered agreement provided only broad outlines, leaving the thorniest political issues unsettled.
During tortuous negotiations to reach a final agreement, tensions between Burhan and Dagalo escalated. A key dispute is over how the RSF would be integrated into the military and who would have ultimate control over fighters and weapons.
Dagalo, whose RSF was involved in brutal crackdowns during tribal unrest and pro-democracy protests, also tried to fashion himself a supporter of the democratic transition. In March, he slammed Burhan, saying military leaders were unwilling to relinquish power.
Analysts argued that Dagalo is trying to whitewash the reputation of his paramilitary force, which began as brutal militias implicated in atrocities in the Darfur conflict.
HOW DID THE SITUATION ESCALATE?
On Wednesday, the RSF began deploying forces around the small town Merowe north of the capital. The town is strategic, with its large airport, central location and downstream electric dam on the Nile River. The next day, the RSF also sent more forces into the capital and other areas of the country, without the army leadership's consent.
On Saturday morning, fighting erupted at a military base south of Khartoum, with each side blaming the other for having initiated the violence. Since then, the military and the RSF have battled each other with heavy weapons, including armored vehicles and truck-mounted machine guns, in densely populated areas of the capital and the adjoining city of Omdurman. The military has pounded RSF bases with airstrikes.
By Monday, dozens of people have been killed and hundreds wounded in the fighting.
The clashes spread to other areas in the country, including the strategic coastal city of Port Sudan on the Red Sea and eastern regions, on the borders with Ethiopia and Eritrea. Fighting was also reported in the war-wrecked Darfur region, where U.N. facilities were attacked and looted. The U.N. says three employees with the World Food Program were killed in the clashes there on Saturday.
WHAT ARE THE PROSPECTS FOR A CEASE-FIRE AND A RETURN TO DIALOGUE?
The prospects for an immediate cease-fire appear to be slim. Burhan and Dagalo have dug in, demanding that the other surrender. The intense nature of the fighting also might make it harder for the two generals to return to negotiations.
On the other hand, the military and the RSF both have foreign backers, who unanimously appealed for an immediate halt to hostilities.
The Muslim religious calendar might also play a role. The fighting erupted during the last week of the Islamic holy month of Ramadan, with the three-day holiday of Eid al-Fitr marking the end of the fasting month later this week. The population is increasingly strained for necessities, many homebound by the violence.
Meanwhile, there has been a flurry of diplomatic contacts. The U.N. Security Council is scheduled to discuss Sudan on Monday.
U.S. Secretary of State Antony Blinken said he discussed the developments in Sudan with the foreign ministers of Saudi Arabia and the United Arab Emirates. The Saudi Foreign Minister said he spoke separately by phone with Burhan and Dagalo, and urged them to stop “all kinds of military escalation."
The Gulf Arab monarchies are close allies to the military as well as the RSF.
Cameron Hudson, a senior associate with the Center for Strategic and International Studies think tank and a former U.S. diplomat, said the Biden administration should get its allies in the region to push for peace.
"Without such pressure, we could find a conflict with the same pattern of the war in Tigray (in Ethiopia ),” he said.
WHO ARE THE FOREIGN ACTORS AND WHAT RESOURCES ARE AT STAKE?
During the decades-long rule of strongman Omar al-Bashir, who was deposed in 2019, Russia was a dominant force. At one point, Moscow reached an initial deal to build a naval base on Sudan's Red Sea cost.
After al-Bashir's ouster, the United States and European nations began competing with Russia for influence in Sudan, which is rich in natural resources, including gold, but has been mired in civil conflicts and military coups. In recent years, the Russian mercenary outfit Wagner has even made inroads in the country.
Burhan and Dagalo have also forged close ties with Saudi Arabia and the United Arab Emirates. Sudanese troops drawn from the military and the RSF have fought alongside the Saudi-led coalition in Yemen’s long-running civil war.
Egypt, another regional power, also has deep ties with the Sudanese military. The two armies conduct regular war games, most recently this month. Egyptian troops were in a Sudanese military base for exercises when the clashes erupted Saturday. They were caught by the RSF which said they would be returned to Egypt.
The military controls most of the country's economy, but the RSF runs major gold mining areas, a key source of income for the powerful group.