The Sudanese army has been at war with rival paramilitaries since April 2023 in a conflict that has killed tens of thousands of people and uprooted more than 12 million, including millions who face a worsening hunger crisis.

"It is for me, yes, another real regret that when it comes to Sudan, we haven't been able on our watch to get to that day of success," Blinken said at a farewell news conference.

There have been "some improvements in getting humanitarian assistance in through our diplomacy, but not an end to the conflict, not an end to the abuses, not an end to the suffering of people," he said.

"We'll keep working at it for the next three days, and I hope the next administration will take that on as well," he said.

The US Treasury Department announced Thursday that it had slapped sanctions on Abdel Fattah al-Burhan, the leader of the Sudanese Armed Forces (SAF), over the military's "lethal attacks" against civilians.

The US Treasury accused the SAF of committing attacks against schools, markets, and hospitals, denying humanitarian access, and using food deprivation as a war tactic.

"Today's action underscores our commitment to seeing an end to this conflict," US Treasury Deputy Secretary Wally Adeyemo said in a statement.

"The United States will continue to use our tools to disrupt the flow of weapons into Sudan and hold these leaders responsible for their blatant disregard of civilian lives," he added.

Since 2023, the SAF has been locked in a battle for control of Sudan against the paramilitary Rapid Support Forces (RSF), led by Burhan's former deputy Mohamed Hamdan Daglo.

Earlier this month, the United States also imposed sanctions against Daglo and the RSF, accusing the group of committing genocide in Sudan's Darfur region.

Across the country, more than 24.6 million people -- around half the population -- face "high levels of acute food insecurity," according to a recent review by the UN-backed Integrated Food Security Phase Classification.