South Carolina Republican Sen. Lindsey Graham has transformed into a staunch defender of President Donald Trump over the last two years, but on Monday morning, he was once again criticizing the president’s policies harshly.

Trump announced his intent Monday morning to withdraw United States forces from northern Syria. This decision would effectively let Turkish forces take over the area.

Graham reacted angrily, saying that this decision will benefit ISIS and Iran.

“ISIS is not defeated, my friend. The biggest lie being told by the administration, that ISIS is defeated,” Graham said on Fox News. “The caliphate is destroyed, but there’s thousands of fighters over there and no, the caliphate would not have been destroyed without the Kurds. And I applaud the president for getting the Kurds and the Arabs to do most of the fighting.”

“The casualties destroying the caliphate was very low. We’ve got less than 1,000 troops in Syria. But this impulsive decision by the president has undone all the gains we’ve made, thrown the region into further chaos, Iran is licking their chops.”

“If I’m an ISIS fighter I have got a second lease on life,” he continued, “So to those who think ISIS has been defeated, you will soon see. And to Turkey, you’ve destroyed the relationship, what little you had, with the U.S. Congress, and I will do everything I can to sanction Turkey’s military and their economy if they step one foot into Syria.”

The South Carolina Republican and the president have had an interesting relationship. During the 2016 election, Graham was strongly critical of Trump, but he has warmed up to him since being in office, defending the president from attacks by Democrats and others.

However, Graham’s hawkish foreign policy views have still lead to him bumping heads with Trump.

Graham has compared Trump’s foreign policy proposals to Obama’s, but Trump hasn’t held back either. In December, the president openly called out Graham, telling him, “Time to focus on our Country & bring our youth back home where they belong!”