Sen. Lindsey Graham (R-S.C.) made a rare move against Donald Trump on Wednesday when he called the president out over the decision to begin the withdrawal of American troops from Syria.

Trump revealed on Twitter that the U.S. had “defeated” the self-described Islamic State terror network in the country, which was his “only reason for” troops “being there” during his presidency.

We have defeated ISIS in Syria, my only reason for being there during the Trump Presidency. — Donald J. Trump (@realDonaldTrump) December 19, 2018

Graham, who only last week said he didn’t see an issue with Trump lying about sex, countered with a tweetstorm warning it “would be a huge Obama-like mistake.”

He said troop withdrawal “mightily undercuts” the effort to contain Iranian expansion and puts “our allies, the Kurds at risk.” Graham also claimed it would “be viewed as a boost to ISIS desire to come back.”

Withdrawal of this small American force in Syria would be a huge Obama-like mistake. https://t.co/atsjHUyJlB — Lindsey Graham (@LindseyGrahamSC) December 19, 2018

With all due respect, ISIS is not defeated in Syria, Iraq, and after just returning from visiting there -- certainly not Afghanistan. — Lindsey Graham (@LindseyGrahamSC) December 19, 2018

President @realDonaldTrump is right to want to contain Iranian expansion.



However, withdrawal of our forces in Syria mightily undercuts that effort and put our allies, the Kurds at risk. — Lindsey Graham (@LindseyGrahamSC) December 19, 2018

A decision to withdraw will also be viewed as a boost to ISIS desire to come back. — Lindsey Graham (@LindseyGrahamSC) December 19, 2018

Graham and five other senators also signed an open letter to Trump expressing their concern over the policy change.

“We believe that 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, (Syrian President) Bashar al Assad, Iran, and Russia.”