Anderson Cooper 360

How Exactly Did We Get To This Point?; Senator Who Spoke With Pres. Trump: The President Appeared Ready To Attack Iranian Facilities If There Had Been Even One U.S. Casualty; Sr. Admin. Official: Iran Reached Out Through At Least 3 Back Channels, Including Switzerland And Other Countries; Sr. Admin. Official: Message From Iran Was Missile Strike Would Be Their Only Response To Death Of Gen. Soleimani; Source: Initial Reaction In WH Situation Room Was One Of Surprise Iranians Fired So Few Missiles Out Of Their Arsenal; Source: U.S. Concerned About Iranian Proxies In Region; Doesn't Buy Iran's Argument They Aren't Responsible For What Proxies Might Do; Deadly Mystery; Uniter Or Divide-In-Chief?; Two Rockets Land In Baghdad's Heavily Fortified Green Zone; Deadly Mystery; Questions surround Ukrainian Plane Crash In Tehran Just Hours After Missile Attacks; Pelosi Under Pressure; Senate Democrats Eager To Start Impeachment Trial; Dems Seek To Limit Pres. Trump's War Powers via Knit