Retired four-star Army Gen. Jack Keane said President Trump's plan to remove U.S. forces from Syria would be a "huge strategic mistake."

In a tweet Wednesday morning and in a subsequent Twitter video, Trump claimed victory over ISIS, explaining that was "my only reason" for supporting 2,200 U.S. troops' presence in the war-torn country.

The move was quickly blasted by Republicans, including Senators Lindsey Graham, Marco Rubio and Bob Corker, and Rep. Adam Kinzinger, who told Fox News he was "absolutely blown away" by the decision. 

On "America's Newsroom" Thursday, Keane agreed with the criticism, saying that if Trump does not reconsider, "he'll come to regret this decision."

"Clearly, we're repeating the Obama mistake of premature withdrawal, which got us ISIS," Keane said.

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He said it's a misstatement to declare that ISIS is defeated in Syria, explaining that the terrorists' safe haven of Raqqa has been taken, but there are still determined, dangerous remnants in the surrounding areas.

"In my judgment, we need to stick to it and finish the job," Keane said.

He explained that ISIS has proven to be resilient, and they have the ability to regroup, rebuild and retake territory.

Keane added that by pulling out of eastern Syria, it essentially gives the country to the Iranians, which will make it their "strategic anchor" in the Middle East.

"That will be a victory of strategic proportions that will have huge consequences for years to come."

Watch the interview above.

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