Sean Spicer, the White House press secretary, told reporters how the resignation happened: “The evolving and eroding level of trust as a result of this situation and a series of other questionable incidents is what led the president to ask General Flynn for his resignation.”
There was somebody this morning who doubted this. Doubt no more.
Trump knew for weeks Michael Flynn misled over Russia contact
https://www.theguardian.com/us-news/2017/feb/14/democrats-russia-trump-investigation-michael-flynn?CMP=Share_iOSApp_Other