Palestinian President Mahmoud Abbas stands as a key obstacle to successful peace talks with Israel, the top U.S. diplomat at the United Nations charged Thursday.

“The United States remains deeply committed to helping the Israelis and the Palestinians reach a historic peace agreement that brings a better future to both peoples,” Ambassador Nikki Haley said during a Security Council meeting. “But we will not chase after a Palestinian leadership that lacks what is needed to achieve peace.”

Haley rebuked Abbas for insulting President Trump and declaring the United States unfit to broker a peace deal, attacks Abbas made following Trump’s recognition of Jerusalem as the capital of Israel. Her denunciation of Abbas coincided with Trump threatening to revoke aid to the Palestinians, if productive talks fail to take place.

“That money is not going to them unless they sit down and negotiate peace,” Trump told reporters, before a meeting with Israeli Prime Minister Benjamin Netanyahu in Davos, Switzerland. “Because I can tell you that Israel does want to make peace. And they’re going to have to want to make peace too, or we’re going to have nothing to do with it any longer.”

That threat might increase pressure on Abbas, who denounced Trump and Haley in mid-January. “We will not accept for the U.S. to be a mediator, because after what they have done to us — a believer shall not be stung twice in the same place,” Abbas said. “Damn your money!”

Haley said that in addition to targeting Trump, Abbas also portrayed the state of Israel “as a colonialist project engineered by European powers” hostile to Palestinians. “A speech that indulges in outrageous and discredited conspiracy theories is not the speech of a person with the courage and the will to seek peace,” she said.

She compared him unfavorably to Egyptian President Anwar Sadat and King Hussein of Jordan, who negotiated treaties with Israel in 1979 and 1994, respectively. “If President Abbas demonstrates he can be that type of leader, we would welcome it,” Haley said. “His recent actions demonstrate the total opposite.”