(JNS) The Palestinian Authority (PA) fired back at President Donald Trump’s tweets on Tuesday that threatened to cut off aid to the Palestinians for their refusal to negotiate with Israel.

“This statement has absolutely no justification. We wanted a peace process with the Americans and we worked hard for it,” Nabil Shaath, PA President Mahmoud Abbas’s international affairs adviser, told The Jerusalem Post.

“We went to the White House to see him and welcomed him here in Bethlehem. But then he recognized Jerusalem as Israel’s capital, taking the single-most important part of negotiations and a two-state solution off the table,” Shaath said. “So he wants to punish us from protesting and not accepting his position on Jerusalem…This [tweet] shows that Trump is not a serious man.”

On Tuesday, as part of a series of tweets on U.S. foreign aid, Trump wrote that “with the Palestinians no longer willing to talk peace, why should we make any of these massive future payments to them?”

Trump’s tweet was followed up by a statement from U.S. Ambassador to the United Nations Nikki Haley, who said, “I think the president has basically said that he doesn’t want to give any additional funding until the Palestinians are agreeing to come back to the negotiation table.”

The U.S. is the largest foreign funder of the PA as well as UNRWA, the U.N. agency dedicated to Palestinian refugees.