"Withdrawing US forces from Syria is a serious strategic mistake. It will leave the American people and homeland less secure, embolden our enemies and weaken important alliances. Unfortunately, the recently announced pullout risks repeating the Obama administration's reckless withdrawal from Iraq, "McConnell wrote in a Washington Post-op.
McConnell added that the combination of the American disadvantage and the fighting between Turkey, which invaded part of northern Syria, and the Kurds created a "strategic nightmare" for the United States.
McConnell's update comes after Vice President Pence announced Thursday that the United States and Turkey had agreed to a five-day firearm, during which the United States will not apply additional sanctions to Turkish officials.
If this holds, the gun would then become permanent and the Trump administration would agree to lift the sanctions they introduced earlier this week.
But McConnell claimed in the Post-Up-Already that even if the arms lifting fails, withdrawing the US troops and Turkey's invasion "would have set back the US campaign against the Islamic State and other terrorists."
"Unless stopped our retreat will invite the brutal Assad regime in Syria and its Iranian supporters to expand its influence. And we are ignoring Russia's efforts to exploit its increasingly dominant position in Syria to gather power and influence throughout the Middle East and beyond, "he added .
McConnell specifically pointed to reports that Russians were filming on abandoned US bases in Syria, calling it a "strategic disaster captured in a Facebook post."
Trump's decision to withdraw US troops, who ban the path of Turkey's invasion, has led to a harsh backlash from traditional GOP allies on Capitol Hill, who called it "catastrophic t ", a" serious mistake "and a" disaster "in creation."
McConnell has repeatedly raised red flags about Trump's decision. He told reporters during a press conference on Wednesday that he had told Trump privately as well as publicly that he disagreed with the decision.
"I don't know how many times I have to say it and I think I speak to most members of my conference that this was a mistake, and I hope it can be repaired," McConnell said at the time.
Trump has defended his decision, saying it's "time for us to get out of these ridiculous Endless Wars."
But McConnell seemed to push back on it on Friday, writing that "America's wars will be 'endless' only if America refuses to win them."
Legislators potentially weigh legislative response to Trump's strategy.
The House passed a resolution this week that formally broke with the decision and is expected to vote next week on sanctions legislation against Turkey.
McConnell has not yet said what, if any, legislation he will be voting for in the Senate floor.
The Senate approved an amendment earlier this year warning the administration against withdrawing troops from Syria or Afghanistan.
McConnell noted the bipartisan support for the amendment in his post op-ed, but added that "unfortunately, the last steps of the administration in Syria do not reflect these crucial lessons."