Washington (CNN) President Donald Trump acknowledged the possibility that ISIS and other terror groups could regain their strength in Syria and Afghanistan if he withdraws or reduces troops in those countries and noted that he would send US forces back if they did.

Trump, who announced in December that he was ordering staff to execute a "full" and "rapid" withdrawal of US troops from Syria, made the comments in an interview taped Friday with CBS's Margaret Brennan on "Face the Nation."

"Because the concern in here by your intelligence chiefs, though, is that you could in that vacuum see a resurgence of ISIS," Brennan said.

"Sure," Trump replied.

"See a resurgence of terror groups like Al-Qaeda," Brennan continued.

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