The White House on Thursday announced economic and visa sanctions against Sudanese leaders it holds responsible for breaking a ceasefire.
"We are following through by levying economic sanctions, imposing visa restrictions against actors who are perpetuating the violence," National Security Advisor Jake Sullivan said in a statement on Thursday.
"Despite a ceasefire agreement, senseless violence has continued across the country – hindering the delivery of humanitarian assistance, and hurting those who need it most.
"The scope and scale of the bloodshed in Khartoum and Darfur, in particular, is appalling," Sullivan said.
Failure by the army and the paramilitary Rapid Support Forces (RSF) to abide by the ceasefire "further deepens our concern that the people of Sudan will once again face a protracted conflict and widespread suffering at the hands of the security forces", he added.
Fighting continued on Thursday, with witnesses reporting heavy artillery in the capital's north.
The army on Wednesday blasted RSF bases in Khartoum after pulling out of the talks in the Saudi city of Jeddah, accusing its rival of violating the ceasefire that was meant to allow aid deliveries.
Fragile situation
The army walked out "because the rebels have never implemented a single one of the provisions of a short-term ceasefire which required their withdrawal from hospitals and residential buildings", a Sudanese government official said.
Secretary of State Antony Blinken, who was in Oslo for NATO talks, said the United States would remain engaged and stopped short of blaming one side for violating the truce, after the army announced its withdrawal on Wednesday.
"We did see the provision of humanitarian assistance going forward. But it has been incredibly imperfect and incredibly fragile," Blinken said.
Earlier this week, US and Saudi mediators said the two sides had agreed to extend the initial week-long humanitarian truce for another five days.
For more than six weeks, Khartoum and other parts of Sudan have been gripped by fighting between the Sudanese armed forces and the paramilitary RSF.
More than 1,800 people have been killed, according to the Armed Conflict Location and Event Data Project.
The UN says 1.2 million people have been internally displaced and more than 425,000 have fled abroad.
(with wires)
