'I knew I had to report this': Top White House aides testify at impeachment hearing

WASHINGTON -- A career Army officer testified Tuesday that President Donald Trump's call with Ukraine was "improper," as Republicans in the impeachment inquiry tried to undercut the national security official with remarkable exchanges questioning his loyalty to the U.S. Lt. Col. Alexander Vindman said that it was his "duty" to report his concerns about the phone call, but deflected repeated Republican efforts to divulge everyone he told about it -- an attempt by GOP lawmakers to identify the ano