Explainer-Why is Sudan at war, and what is the impact?

April 15 (Reuters) - The war in Sudan entered its fourth year on April 15 overshadowed by other regional and global turmoil, despite having created what the United Nations calls the world's worst humanitarian crisis.

WHO IS FIGHTING?

The war pits the Sudanese army, led by General Abdel Fattah al-Burhan, against the Rapid Support Forces, a paramilitary group led by General Mohamed Hamdan Dagalo.

The two men had joined forces in 2019 to overthrow veteran autocrat Omar al-Bashir, after which Burhan became head of state. But having staged a coup that derailed a faltering transition towards civilian rule, they fell out over plans to launch a new transition and integrate their forces.

After war erupted on April 15, 2023, it quickly drew in myriad local militias fighting on either side, as well as foreign powers.

Most prominently, U.N. researchers, U.S. lawmakers, and the Sudanese army say the United Arab Emirates has provided critical support to the RSF via several of Sudan's neighbors, a charge the Gulf power denies.

The Sudanese army counts other regional powers including Egypt, Turkey, Saudi Arabia, and Qatar as supporters to varying extents.

WHAT IS THE STATE OF PLAY?

The RSF last year cemented control of the vast Darfur region, its traditional power base and the westernmost area of the country, and quickly began setting up a parallel government. The army maintains control over the eastern half of the country.

The fight is currently centered around the Kordofan region that lies in between, as well as a new front opened up by the RSF along the Sudanese border with Ethiopia in the southeast.

Drone warfare has displaced ground campaigns as the primary mode of fighting, and has allowed the RSF to overcome the army's previous air dominance. Like the shelling and bombardments that marked the war's earlier stages, it has also added to the human toll of the conflict, claiming at least 700 civilian lives this year, according to the U.N.

HOW HAVE CIVILIANS BEEN IMPACTED?

The war has had a devastating impact on the Sudanese people, with the U.N. estimating that almost three-quarters are in need of humanitarian aid.

Famine or risk of famine has been declared in conflict hotspots across the country, often exacerbated by blockades and bureaucratic impediments placed by the warring parties.

Diseases including dengue fever have run rampant as the country's healthcare system collapsed in many areas.

Throughout the war, the RSF has carried out waves of ethnically targeted killings later cited as bearing the hallmarks of genocide by U.N. researchers, most recently in North Darfur's al-Fashir.

Violence and reduced funding have prevented the calculation of a comprehensive death toll. Sudan's health ministry tells Reuters it has documented 11,209 deaths across most of Sudan's states, but experts say excess deaths since the war began are in the hundreds of thousands.

Despite overwhelming need, the U.N.'s 2026appeal for aid to Sudan is only 17% funded, coming at a time when the U.S. has retreated from foreign aid, European donors make cuts, and Gulf powers focus on bilateral donations.

Aid agencies report scaling back their services, while Sudanese mutual aid groups, including the Nobel Peace Prize-nominated Emergency Response Rooms, have tried to fill the gap.

A study by aid agency Islamic Relief this week, however, showed that more than 40% of the local community kitchens run by these groupshave had to shut down due to lack of support.

WHAT'S BEING DONE TO STOP THE WAR?

While the war has caught the attention of world leaders, including U.S. President Donald Trump, few attempts to end it have shown promise and competing regional interests have hindered efforts.

The U.S. has led a so-called Quad that includes Egypt, Saudi Arabia, and the United Arab Emirates, which presented a preliminary proposal for a ceasefire to both sides last year.

As realities on the ground have changed, both the army and RSF have by turns welcomed and rejected mediation, with no let-up in fighting on the horizon.

(Writing by Nafisa Eltahir and Khalid Abdelaziz; Editing by Aidan Lewis)