The origins of the impeachment inquiry engulfing President Trump and his administration go back to the election this spring of a new Ukrainian president, Volodymyr Zelensky. Over the next five months, White House emissaries pressured Mr. Zelensky to announce that Ukraine would investigate two matters: Burisma Holdings, a Ukrainian gas company that hired Hunter Biden, the younger son of former Vice President Joseph R. Biden Jr., and whether Ukraine had meddled in the 2016 American presidential election.
New York Times: Key dates at the center of the Ukraine matter
US President Donald Trump offers a hand shake to Ukrainian President Volodymyr Zelensky during a meeting in New York on September 25, 2019, on the sidelines of the United Nations General Assembly.