Dr Fiona Hill, an official who is also an expert on Russia, gave strong testimony at the Impeachment Inquiry Thursday (11-21-19). I think she was clear, nonpartisan, and confident with a bit of ice breaking wit added to the mix. She withstood some ridiculous attacks from Republicans as they clearly tried to defend Trump.
It appears to me that at the time, Dr Hill saw that a political agenda was going on from Trump Administration officials in the Ukraine situation which went against appropriate national security diplomacy. Dr Hill indicated that she was also concerned at the time that national security itself could potentially be compromised by the goings on.
She also admonished those (a number of Republicans) for promoting outrageous conspiracy theories which she pointed out were created by Russian security services themselves. Dr Hill pointed out that Russia (not Ukraine) interfered in the 2016 election and is gearing up to do it again in 2020.
In my opinion, the testimony of multiple witnesses is showing clear wrongdoing on the part of the Trump Administration in regards to the Ukraine situation. I think there was inappropriate pressure placed on the Ukrainian government to try to get them to dig up dirt on Biden for political purposes and that the threat of withholding Congressionally approved aid and a White House meeting was their way of doing it.
Trying to pressure a foreign government to dig up dirt on a political rival by threatening to withhold government aid is absolutely wrong! https://www.usatoday.com/story/news/politics/2019/11/21/top-moments-fiona-hills-impeachment-hearing-show-outspoken-nonpartisan/4261353002/ https://amp.cnn.com/cnn/2019/11/22/politics/donald-trump-fiona-hill-impeachment-ukraine/index.html