Despite pushback from the Pentagon, U.S. President Donald Trump has ordered a “full” and “rapid” withdrawal of American troops in Syria, a U.S. defense official told CNN on Wednesday.

“We have defeated ISIS in Syria, my only reason for being there during the Trump Presidency,” tweeted the president.

“Five years ago, ISIS was a very powerful and dangerous force in the Middle East, and now the United States has defeated the territorial caliphate. These victories over ISIS in Syria do not signal the end of the Global Coalition or its campaign,” said White House press secretary Sarah Sanders in a statement. “We have started returning United States troops home as we transition to the next phase of this campaign.”

“The United States and our allies stand ready to re-engage at all levels to defend American interests whenever necessary, and we will continue to work together to deny radical Islamist terrorists territory, funding, support and any means of infiltrating our borders,” she said.

However, Pentagon spokesperson Col. Rob Manning told CNN that “at this time, we continue to work by, with and through our partners in the region.”

Israeli Prime Minister Benjamin Netanyahu said he spoke with Trump and Secretary of State Mike Pompeo ahead of the announcement. The Israeli leader has been reported as saying that he plans to study the decision, as well as its implications, and that Israel will continue to “defend ourselves in this area.”

Israeli Ambassador Danny Danon said that Israel would respect any Trump administration decision, though Israel is concerned about Iran’s presence in Syria and that the Jewish state would do, in collaboration with its own allies, to protect Israel if needed.

Trump’s decision evoked mixed reactions from members of Congress to Mideast scholars.

In response to Trump’s tweet, Rep. Adam Kinzinger (R-Ill.) responded: “This is simply not true.”

“Iran is rejoicing right now. We left Iraq, and had to come back,” Kinzinger previously posted on Twitter. “I would sure hope the President and his advisers are smarter than this.”

Sen. Lindsey Graham (R-S.C.) echoed Kinzinger’s sentiment, saying that “withdrawal of this small American force in Syria would be a huge Obama-like mistake.”

“With all due respect, ISIS is not defeated in Syria, Iraq, and after just returning from visiting there—certainly not Afghanistan,” he said in a Twitter thread. “President [Trump] is right to want to contain Iranian expansion. However, withdrawal of our forces in Syria mightily undercuts that effort and put our allies, the Kurds at risk. A decision to withdraw will also be viewed as a boost to ISIS desire to come back. Withdrawal of this small American force in Syria would be a huge Obama-like mistake.”

“Idiotic move by President Trump,” tweeted Foundation for Defense of Democracies chief executive Mark Dubowitz. “And let’s be clear: this is all on him. Can’t imagine anyone else of note supported this move.”

“One can only hope any U.S. military withdrawal from Syria would not be unconditional. It would be strategically and morally wrong to leave Syrian Kurds to their fate vs Turkey,” said Council on Foreign Relations president Richard Haas. “Same holds for leaving Syrian people to face their government, Iran and Russia.”

Meanwhile, those such as Sen. Rand Paul (R-Ky.) approved of the decision.

“I am happy to see a President who can declare victory and bring our troops out of a war,” he tweeted. “It’s been a long time since that has happened.”

Rep. Justin Amash (R-Mich.) posted on Twitter: “U.S. forces should not be engaged in Syria—or any country—without legitimate military justification AND proper congressional authorization.

“Despite cosmic oyveys from neocons/liberal interventionists, the US mission in Syria lacks focus and clarity beyond keeping ISIS down. Putin, Assad and Iran have already won,” tweeted former State Department adviser Aaron David Miller. “What is the purpose of 2000 forces; and what is our end game. If we don’t know, what are we doing there?”

“We cannot accomplish any of our fantastical goals with 2000 troops—checking Russians; beating back Iran, leveraging Assad out of power, Give me compelling reason to stay,” he added.