Iran tensions and impeachment dominate Washington

Former Trump national security adviser John Bolton says he will testify in a Senate impeachment trial if he is subpoenaed. Meanwhile, tensions are high as Iran vows revenge for the death of top general killed in a U.S. airstrike. CBS News national security correspondent David Martin, White House correspondent Weijia Jiang, and CBSN political contributor Molly Hooper joined CBSN to discuss.