Prominent actor George Clooney and human rights activist John Prendergast are the co-founders of The Sentry, an organization that tracks corruption and conflict. Now they’ve appealed to the United States government to act on the Sudan crisis with sanctions and anti-money laundering measures.

The two wrote an appeal in a Politico op-ed that condemns the impunity that Sudanese actors have known for decades, and decries the security forces and Janjaweed militia groups that have attacked pro-democracy forces since the removal of former president Omar al-Bashir in April.

“If this sounds like another hopeless African crisis, it isn’t. Sudan is a country that has unified Republicans and Democrats in Congress and successive administrations in Washington in defense of human rights and peace,” the op-ed authors said. “Much more can be done now by the current Congress and the Trump administration—as well as allies in Europe and Africa—to create consequences for the leaders of the regime and the Janjaweed destroying and looting the country.”

The piece was written as U.S. Assistant Secretary of State for African Affairs Tibor Nagy headed for Khartoum, where he has arrived with Ambassador Donald Booth, a new special envoy for Sudan.

“He will bring his extensive experience to the task of supporting a political solution to the current crisis that reflects the will of the Sudanese people,” Nagy said of Booth. “He is with me in Khartoum today as we push for an end to attacks on civilians and for a transition to civilian-led transition.”

Those negotiations are likely to begin again, according to some reports, but the violence in Sudan – and its long history – are cause for alarm as Nagy visits.

“His diplomatic entreaties will fall on deaf ears if not backed by the unique power that U.S. Treasury Department actions can have over the kind of illicit financial activity that Sudan’s leaders have been engaged in for years,” said Clooney and Prendergast.

The complete Politico op-ed is available here.