Rep. Liz Cheney (R-Wyo.), a member of House leadership who is weighing a Senate bid, called Trump's decision a "catastrophic mistake that puts our gains against ISIS at risk and threatens US security."
"This decision ignores lesson of 9/11. Terrorists thousands of miles away can and will use their safe-havens to launch attacks against America," she added in a tweet.
Rep. Adam Kizinger (R-Ill.) said withdrawing U.S. troops from the area would "abandon our friends and give Russia & Iran exactly what they want. This is wrong."
And Rep. Pete King (R-N.Y.), who sits on both the Intelligence and Homeland Security Committees, also voiced his disapproval. "Strongly disagree with @POTUS Trump decision to allow Erdogan to invade Syria. Betrays Kurds, strengthens ISIS and endangers American homeland," King tweeted.