Biden says Trump and his political appointees have blocked national security transition work, posing threats to the U.S. - The Washington Post

..."Right now, we just aren't getting all the information that we need from the outgoing administration in key national security areas. It's nothing short, in my view, of irresponsibility," Biden said of the resistance his teams were facing. He warned that such delays could allow enemies of the United States to take advantage of vulnerabilities, citing a massive cybersecurity breach that compromised several U.S. agencies earlier this month...

https://www.washingtonpost.com/politics/biden-trump-obstruction/2020/12/28/d4dd6e7e-4925-11eb-839a-cf4ba7b7c48c_story.html