From the story here:
A top Republican senator said Wednesday that it appears former FBI Director James B. Comey leaked classified information in his effort to shape the narrative surrounding President Trump’s decision to fire him. ... He said he’s personally reviewed the seven memos, but was forced to do so in a Sensitive Compartmented Information Facility, or SCIF. “The FBI insisted that these reviews take place in a SCIF because the majority of the memos are classified,” he said. “FBI personnel refused to answer factual questions during the document reviews, including questions about the chain of custody of the documents I was reviewing, the date that they were marked classified, and who marked them as classified.”
