Though the Biden campaign indicated that they would respond to the Intercept's questions, they have not done so.
Much of this controversy centers on Biden's aggressive efforts while Vice President in late 2015 to force the Ukrainian government to fire its Chief Prosecutor, Viktor Shokhin, and replace him with someone acceptable to the U.S... These events are undisputed by virtue of a video of Biden boasting in front of an audience of how he flew to Kiev and forced the Ukrainians to fire Shokhin, upon pain of losing $1 billion in aid.