How halting Ukraine aid, as described by Laura Cooper, knocks down Trump's defenses - The Washington Post

“Laura Cooper, a senior defense official, told House impeachment investigators last month that the Pentagon sought clarification from the Trump administration on July 18 about the hold-up of aid to Ukraine.” She tried to figure out why, and “at a July 23 meeting, the Office of Management and Budget told agencies that ‘the White House chief of staff has conveyed that the president has concerns about Ukraine and Ukraine security assistance.’" Later, Cooper learned from U.S. special envoy to Ukraine Kurt Volker that this was about eliciting a statement from Ukraine. That would be a statement specifying the Bidens. “Asked if Volker indicated that success would ‘lift this issue’ of the hold on military aid, Cooper said ‘yes.’ ” ...
https://www.washingtonpost.com/opinions/2019/11/12/hold-how-holding-up-ukraines-aid-ensnares-trump/