He pointed to intelligence failures over the existence of WMDs (weapons of mass destruction) in Iraq before the U.S. invasion, and declared himself an expert in the area.

In remarks to reporters at his New Year's Eve party in Florida, reported by the Associated Press, the president-elect suggested an alternative means of communication.

Republican John McCain, chairman of the Senate Armed Services Committee, has scheduled a Thursday hearing on foreign cyberthreats. Intelligence officials reportedly claimed that the plan was always for the heads of the CIA, NSA, FBI as well as the DNI to brief Trump on Russian hacking on Friday.

On Sunday, Spicer said the White House may have disproportionately punished Russian Federation. The United States should impose more sanctions on Russian Federation over its alleged role in USA election campaign hacks, a senior House of Representatives member said in an ABC broadcast.

Mr Spicer said: "One of the questions that we have is why the magnitude of this?" The Obama administration also expelled 35 Russian intelligence operatives from the country, and restricted access to two Russian diplomatic compounds. "Maybe it was; maybe it wasn't but you have to think about that", Spicer said. "And you're going to see bipartisan support in Congress for stronger sanctions against Russian Federation". Nothing, nothing was taken when millions of people had their private information, including information on security clearances that was shared. "Not one thing happened", he said.

At a special briefing that followed the announcement, United States administration officials admitted that Trump can easily reverse the sanctions imposed by his predecessor. "I don't care what they say, no computer is safe".

"Really wish we saw more PEOTUS respect for our intelligence professionals", Warner said on Twitter.

Democratic Rep. Adam Schiff of California of the House Intelligence committee called Trump's comments "dangerous", adding that the proof is "solid".

The "intelligence community is talking about wrapping it up later this week. the idea that we are jumping to conclusions before we have a final report is frankly irresponsible". But the upgrade may not win over Mr. Trump who say no computer is safe.

The fresh clash came as Trump promised to hold his first formal news conference since his election victory next week in NY. The new Congress, elected on 8 November, takes office on Tuesday.

Cyber warfare is a conflict we can't afford to lose.