Secretary of State Antony Blinken warned Thursday that the United States could take action against rival Sudanese leaders after the collapse of a US-brokered truce.
The United States is "looking at steps that we can take to make clear our views on any leaders for taking Sudan in the wrong direction," Blinken told reporters at NATO talks in Oslo.
The Sudan army on Wednesday blasted bases of the paramilitary Rapid Support Forces (RSF) after pulling out of the truce talks in the Saudi city of Jeddah, accusing its rival of breaching the ceasefire meant to bring in aid.
The US said there had been "serious violations of the ceasefire by both sides".
"Once the forces make clear by their actions that they are serious about complying with the ceasefire, the United States and the Kingdom of Saudi Arabia are prepared to resume facilitation of the suspended discussions to find a negotiated solution to this conflict," a State Department spokesperson said earlier on Thursday.
"These violations have led us as a facilitator of these talks to seriously question whether the parties are ready to take the actions needed to meet the obligations they have undertaken on behalf of the Sudanese people," he said.
In both north and south Khartoum on Wednesday, troops loyal to army chief Abdel Fattah al-Burhan attacked key bases of the RSF led by commander Mohamed Hamdan Daglo.
One witness said there was "heavy artillery fire from army camps" in the capital's north, on the 47th day of a war that researchers said has claimed 1,800 lives.
Another reported "artillery blasts on the RSF camp in Al-Salha" in southern Khartoum - the largest paramilitary base and arsenal in the city.
The attacks came two days after the United States and Saudi mediators said the warring parties had agreed to extend by five days the initial week-long humanitarian truce.
The mediators of the talks in Jeddah acknowledged repeated breaches but have held off imposing any sanctions.
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 on condition of anonymity.
Mediators admitted the truce had been "imperfectly observed", but said the extension would "permit further humanitarian efforts".