Alexander Vindman: Key impeachment witness to retire from army over 'intimidation' led by Trump

Read MoreA key witness in the impeachment proceedings against Donald Trump is retiring from the US army after 21 years of service, citing a “campaign of bullying” from the White House.A key witness in the impeachment proceedings against Donald Trump is retiring from the US army after 21 years of service, citing a “campaign of bullying” from the White House.