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.
Russia denies hacking alleged to have helped Mr Trump defeat Hillary Clinton.
Late on Thursday, Mr Trump questioned how intelligence agencies were confident about the alleged Russian hacking “if they never even requested an examination of the computer servers” belonging to the Democratic National Committee (DNC).