https://nypost.com/2020/09/16/biden-hits-trump-administration-in-leaked-call-with-poroshenko/
As a result, he said, he had withheld some information regarding Ukraine from his counterparts in the Trump transition team.
“And the people they put forward to be part of the transition have to be cleared to do that, just as we had to be cleared after the Bush administration, etc. They have not done that, they’re trying to catch up and do it now since they fired the guy who headed up the transition just last week. The reason I bother to tell you that is I have been somewhat limited on what I am able to tell their team about Ukraine,” he admitted.
“The truth of the matter is that the incoming administration doesn’t know a great deal about the situation. So I am meeting with the vice president-elect, who is the only one who has any foreign policy experience,” he added, speaking of Vice President Mike Pence