The United States on Thursday imposed sanctions on companies it accused of fueling the conflict in Sudan.

The US Treasury Department said in a statement it targeted two companies affiliated with Sudan’s army and two companies affiliated with the rival paramilitary Rapid Support Forces (RSF), accusing them of generating revenue from the conflict and contributing to the fighting.

“Through sanctions, we are cutting off key financial flows to both the Rapid Support Forces and the Sudanese Armed Forces, depriving them of resources needed to pay soldiers, rearm, resupply, and wage war in Sudan,” Treasury Secretary Janet Yellen said in the statement.

“The United States stands on the side of civilians against those who perpetuate violence towards the people of Sudan.”

Saudi Arabia and the United States have been leading efforts to try to secure an effective ceasefire in Sudan.

Thursday’s action marks the first punitive measures imposed under an executive order signed by US President Joe Biden in May that paved the way for new Sudan-related sanctions amid the fighting.

The conflict, which broke out on April 15, has killed hundreds, displaced more than 1.2 million people inside Sudan and driven 400,000 others across borders to neighboring states, the United Nations says.

Washington targeted Algunade, which it said is a Sudanese holding company controlled by RSF Commander Mohamed Hamdan Dagalo and his brother; Tradive General Trading L.L.C., a front company controlled by RSF Major Algoney Hamdan Dagalo, another brother; Sudan’s largest defense enterprise Defense Industries System; and arms company Sudan Master Technology.

Washington also issued an updated business advisory to highlight growing risks to US business and individuals exacerbated by the conflict, including trade in gold from a conflict-affected area, US Secretary of State Antony Blinken said in a separate statement.

He added that visa restrictions were imposed on individuals in Sudan, including officials from both the army and RSF and leaders from the former Omar al-Bashir government.

“The ongoing fighting in Sudan between the Sudanese Armed Forces and the Rapid Support Forces is a tragedy that has already stolen far too many lives – it must end,” White House national security adviser Jake Sullivan said Thursday.

“These measures are intended to hold accountable those responsible for undermining the peace, security, and stability of Sudan.”

Sudan’s army suspended talks with the rival paramilitary force on Wednesday over a ceasefire and aid access, raising fears the six-week-old conflict will push Africa’s third largest nation deeper into a humanitarian crisis.