Former President Jimmy Carter sharply criticized President Obama for his handling of foreign policy yesterday, saying it’s often “hard to figure out what his policy is.”

In an interview with the Fort Worth Star-Telegram, the nation’s 39th president accused Obama of violating the U.S. Constitution with drone strikes that killed Americans.

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On the current threat of ISIS, Carter wasn’t any kinder to Obama. “First of all, we waited too long,” he said. “We let the Islamic State build up its money, capability and strength and weapons while it was still in Syria.”

Last month, the former Nobel Peace Prize winner came out in favor of attacking the Islamic State.