http://www.vox.com/2016/11/17/13673280/mike-flynn-trump-new-national-security-adviser-russia-isis-obama-clinton-turkey
"Flynn had also been considered for defense secretary, but his new appointment as national security adviser, which doesn’t require congressional approval, allows Trump to sidestep what would have likely been a bruising, two-step confirmation battle on Capitol Hill. Flynn, who ran the Defense Intelligence Agency until retiring in 2014, would have first needed a congressional waiver to get around rules requiring former military officers to be out of uniform for seven years before taking the top post at the Pentagon. He’d then have needed to win the approval of at least 51 lawmakers. Even with the Senate in Republican control, that wouldn’t have been a sure thing. Democrats would have lashed into Flynn because he broke with the longstanding tradition of retired officers avoiding direct criticism of presidents they had served. Republicans would have pressed Flynn about Trump’s stated Russia policy, which is predicated on building closer ties with Putin despite the Russian strongman’s human rights violations and annexation of Crimea. Republican lawmakers would also likely have grilled Flynn about his decision to do a paid series of events in Moscow that included a speech and an appearance at an anniversary party for RT, a Kremlin-funded TV station, where he was photographed sitting next to Putin."
