US Vice-President Joe Biden has told President-elect Donald Trump to "grow up" and criticised his attacks on the intelligence community.
On Friday, Mr Trump will be briefed on allegations Russia meddled in the US presidential election - claims he has cast doubt on.
Mr Biden said it was "absolutely mindless" for the president-elect not to have faith in intelligence agencies.
For a president not to have confidence in, not to be prepared to listen to, the myriad intelligence agencies, from defence intelligence to the CIA, is absolutely mindless," he said*in an interviewwith the PBS network.
"The idea that you may know more than the intelligence community knows - it's like saying I know more about physics than my professor. I didn't read the book, I just know I know more."
When asked what he thought of Mr Trump's regular attacks on Twitter, Mr Biden said: "Grow up Donald, grow up, time to be an adult, you're president. Time to do something. Show us what you have."