CIA says Istanbul airport attack bears hallmarks of Islamic State

WASHINGTON (Reuters) - The head of the Central Intelligence Agency John Brennan said on Wednesday an attack at Istanbul airport bore the hallmarks of Islamic State's "depravity." The CIA director also said the United Kingdom's Brexit vote may present the European Union with its biggest challenge. (Reporting by Jonathan Landay and Warren Strobel; Writing by Yara Bayoumy; Editing by Chris Reese)