Dec. 19 (UPI) -- U.S. troops have been training local forces to combat Islamic State militants in Syria, also known by the acronyms ISIS and ISIL. The withdrawal will be "full" and "rapid," CNN reported.
President Donald Trump announced the pullout on Twitter on Wednesday morning, writing "we have defeated ISIS in Syria, my only reason for being there during the Trump Presidency" and followed it up nine hours later with a Twitter video message that "after historic victories against ISIS, it's time to bring our great young people home!"
Several members of Congress sent a letter to Trump asking him to reverse his decision, saying "such action at this time is a premature and costly mistake that not only threatens the safety and security of the United States, but also emboldens ISIS, Bashar al Assad, Iran and Russia." Signees were Republicans Lindsey Graham of South Carolina, Joni Ernst of Iowa, Marco Rubio of Florida and Tom Cotton of Arkansas, and Democratic Sen. Jeanne Shaheen of New Hampshire and independent Sen. Angus King of Vermont.
Graham, speaking on the Senate floor Wednesday night, called the change in policy "disastrous to our own national security."
"We have been dishonorable. This is a stain on the honor of the United States," said Graham, who has been a frequent supporter of Trump.
The senator, who recently came back from Afghanistan, said "I'm not saying we need to be in Syria forever. I'm saying now's not time to leave."
White House spokeswoman Sarah Sanders earlier acknowledged the pullout in a statement Wednesday.
"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," she said. "These victories over ISIS in Syria do not signal the end of the Global Coalition or its campaign.
"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."
Partners in northeast Syria have been told of the withdrawal, a senior administration official told reporters. The Pentagon, though, will maintain about 5,000 troops in neighboring Iraq and the ability to launch attacks into Syria, if needed. The Syrian government has long called for U.S. forces to leave the country.
The official said about 1 percent of the Islamic State remains active in Syria, a figure the United States believes can be eliminated by regional partners.
"We are under no illusions that ISIS at large or the scourge of Sunni tyranny has gone away," the administration official said.
The official offered no timeline for how quickly troops will be removed from Syria or how many have already left.
The announcement appeared to indicate a sudden shift in U.S. policy toward the Middle East. Earlier this month, the U.S.-led coalition said there were no plans for a change.
"Any reports indicating a change in the U.S. position with respect is false and designed to sow confusion and chaos," the coalition said in a statement.
News of a U.S. pullout comes a day after Russia, Iran and Turkey agreed that a panel to draw up a new Syrian Constitution will meet next month.
Diplomats from the three countries agreed at the end of a meeting in Switzerland on Tuesday the 150-body committee will convene for the first time in January.
"We have agreed to take efforts aimed at convening the first session of the Syrian constitution committee early next year," Russian Foreign Minister Sergey Lavrov said in a statement after the meeting.
"These steps will lead to the launch of a viable and lasting Syrian-owned, Syrian-led, U.N.-facilitated political process."
The body was expected to have 50 representatives from the Syrian government, 50 representatives from the opposition, and 50 "independent" delegates picked by the United Nations. The Syrian government, though, pushed back on the independent candidates' portion and objected outright to some of the U.N. delegates.
The creation of a new Constitution for Syria is at the center of the country's seven-year civil war and a political struggle by Assad. The United States has rejected any proposed peace deal that leaves him in power.
Assad said a new Syrian Constitution is not needed and the existing law only needs tweaking, The New Arab reported. The United Nations and United States believe a new Constitution is needed to guarantee free elections.
Syria's civil war has lasted for seven years and has killed more than 500,000 people. Millions more have fled their homes in the war-ravaged country.
"Slowly, we are reaching a conclusion," Turkish Foreign Minister Mevlut Cavusoglu said. "We have reached an important step in our work toward the Syrian constitutional committee."