Russian President Vladimir Putin is a bigger threat to world security than the so-called Daesh, according to veteran US Senator John McCain who also admits Donald Trump makes him "nervous".
Republican McCain -- one of US President Trump´s most outspoken critics in his own party -- said Russia´s alleged meddling in elections was a danger to democracy.
"I think he (Putin) is the premier and most important threat, more so than ISIS," McCain, chairman of the Senate Armed Services Committee, told the Australian Broadcasting Corporation late Monday.
"I think ISIS can do terrible things ... but it is the Russians who are trying, who tried to destroy the very fundamental of democracy and that is to change the outcome of an American election.
"I have seen no evidence they succeeded but they tried and they are still trying. They just tried to affect the outcome of the French election.
"So I view Vladimir Putin, who has dismembered the Ukraine, a sovereign nation, who is putting pressure on the Baltics, I view the Russians as the far greatest challenge that we have."
McCain´s comments come with the Trump team embroiled in controversy over its relationship with Moscow, which US intelligence agencies say tried to sway last November´s election in the property tycoon´s favour.
A broad investigation into Russia´s apparent meddling is being led by Robert Mueller, a respected former FBI director who was given wide powers to pursue the case as a special counsel.
The US Senate and House Intelligence committees are also leading their own probes.