The U.S. Justice Department’s inspector general released a long-anticipated report Monday scrutinizing the roots of the Russia investigation, concluding that while the FBI was justified in opening a probe into whether anyone tied to the Trump campaign coordinated with the Kremlin, there were “serious performance failures” in obtaining surveillance warrants against a former Trump aide.

The department’s inspector general, Michael Horowitz, spent more than a year scrutinizing the early steps of the Russia investigation, a probe Trump and his allies have derided repeatedly as a “hoax” and “witch hunt.”