[I]t has been vexing for Mr. McCain to be battling persistent — and false — Internet rumors that he not only helped invent [ISIS] but also knows its leader, Abu Bakr al-Baghdadi, the self-proclaimed caliph of the Muslim world and America’s latest Public Enemy No. 1.
The rumors are based partly on images of a Syrian fighter who resembles Mr. Baghdadi, seen in photographs with Mr. McCain — some originally posted on Twitter by the senator — during his visit in May 2013 to northern Syria.
https://www.snopes.com/fact-check/john-mccain-meets-isis-leader/