Monday on the NewsHour, Iran mourns Gen. Qassem Soleimani, killed by the U.S. in an airstrike on Friday. Plus: Possible political and military repercussions of the Soleimani killing, a Senate impeachment trial in limbo, 2020 Democrats focus on foreign policy amid Iran tensions, Politics Monday with Tamara Keith and Lisa Lerer, political upheaval in Venezuela and refugee artists in exile in France.