officials raising similar issues despite the president trying to discredit them. >> reporter: lieutenant colonel alexander vindman wearing his formal army service urn form was a stark reminder approaching his testimony today not as a political official but a senior member of the u.s. military. an expert on ukraine, his country of birth, then part of the soviet union. >> some people might call that espionage. >> his story leading some republicans to question his patriotism. the damning testimony in this impeachment inquiry has been all the more powerful because like vindman it is coming with people from years of service working with administrations from both parties. >> because of the love of country and the oath of office and the oeb and the -- the oath to its constitution. >> reporter: ambassador bill taylor came out of retirement after a 30-year career in the foreign service hand picked by secretary of state mike pompeo to help the trump administration