The senior official said he saw Erdogan as a long-time tyrant, and that relations between Washington and Ankara were unlikely to improve as long as Erdogan was in power.
Relations between NATO allies have been strained, especially after Ankara's acquisition of Russian missiles designed primarily to target NATO planes, adding to the tensions that have almost reached the point of Erdogan's attack on northern and eastern Syria, an ally of the International Coalition against ISIS.
The Wall Street Journal reported that US military officials watched a video of Turkish-backed mercenaries targeting civilians in Syria, which amounted to war crimes. Following reports of field executions and the use of white phosphorus by Turkish-backed mercenaries.
"Trump is weak and can be easily manipulated. Erdogan has found a way to do this," David Phillips, director of the Columbia University's Peacebuilding and Rights Program, who served as top State Department adviser under Presidents Bill Clinton, George W. Bush and Barack Obama, was quoted as saying.
Phillips described Erdogan as a tyrant and his mercenaries committed war crimes in Kurdish areas against civilians in Afrin.
Phillips said: "The crimes committed by FSA mercenaries is the responsibility of Erdogan; FSA under the leadership of Turkey."
Phillips outlined policy steps that would marginalize the Turkish government and could lead to regime change. First, the United Nations or any other independent body should be urged to hold Erdogan accountable.
"Erdogan should not be in the White House. He should be in The Hague before the judges for the crimes he has committed," Phillips said.
Second, the US Congress should go ahead with measures against Turkey to buy the S-400 under the US adversaries through sanctions bill and the second sanctions bill for its attack on Syria.
Phillips said Turkey was responding only to coercion. "Turkey is not now a friend of the United States. We have to stop pretending. The only way to change Turkey's behavior is to be tough with Erdogan. I don't think Trump has the strength and the intention to do that."
The third step for the United States would be to get its nuclear weapons out of Incirlik Air Base in southern Turkey.
He said the fourth step would be to move Turkey's EU accession talks from suspension to the end of its EU accession.
"The loss of Turkey is not a big problem. We are willing to bear this cost, in order to rally the public in Turkey to serve an alternative system."
"We have already lost Turkey as long as Erdogan remains president, and the likelihood of improved relations between the United States and Turkey will remain limited. We need regime change, not only in Turkey, but in the United States, to get this relationship back on track," he said.