National Security Advisor Michael Flynn has resigned over controversy surrounding his ties with Russia. The military veteran stepped down late on Monday night less than a month into President Donald Trump's administration amid mounting questions over his future and his close links with the Kremlin. His stunning announcement, first reported by CNN, came just hours after sources close to the government revealed that the Justice Department had warned the new administration that his links with the Kremlin had put him in a compromising position and left him open to blackmail.