Tonight on the Last Word: President Trump justifies his decision to carry out an airstrike against an Iranian general by claiming it was an act of self-defense. Mitch McConnell and Chuck Schumer speak about Trump’s impeachment trial on the Senate floor. Also, the New York Times reports that the White House is withholding emails between two Trump aides about the freeze of Ukraine’s military aid. Plus, Ali Soufan joins Ali to analyze Trump’s Iran war strategies. And Yamiche Alcindor and Rick Wilson return to discuss how the current Iran crisis will affect the 2020 campaign trail. Ali Arouzi, Ben Rhodes, Brett McGurk, Glenn Kirschner and Fmr. Rep. Tom Coleman also join Ali Velshi.