Brennan said that he first picked up on Russia's active meddling last summer and, in an August 4, 2016, phone call with Alexander Bortnikov, the head of Russia's FSB intelligence agency, warned him against further interference. Bortnikov, Brennan said, denied any active efforts in the election.

http://www.cnn.com/2017/05/23/politics/john-brennan-house-intelligence-committee/