Video link: 170529McCain_desk.mp4
Russia's leader Vladimir Putin is a bigger threat to the United States than islamist terrorism, US senator John McCain says.
Speaking to the ABC's 7.30 program on Monday night, Mr McCain - who is in Canberra for security talks - said Mr Putin is "the premier and most important threat, more so than ISIS".
"I think ISIS can do terrible things, and I worry a lot about what is happening with the Muslim faith," Mr McCain said.
"But it's the Russians 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.
The Federal Bureau of Investigation (FBI) began examining possible Russian interference in the 2016 election, before FBI head James Comey was fired by President Donald Trump.
Mr Putin has denied Russia attempted to meddle in the election.
Despite this, Mr McCain said there should be further sanctions on "the Russians" as they are "the far greatest challenge that we have".
"We need to have increased sanctions and hopefully when we come back from our recess the Senate will move forward with sanctions on Russia, and enact other penalties for Russian behaviour," Mr McCain said.
The 80-year-old, who is the chair of the senate armed services committee, also addressed mounting tensions with North Korea, saying the world could face another Cuban Missile Crisis if tensions are not diffused.
"The key to it is China. China can restrain North Korean behaviour," Mr McCain said. "This could be a very serious crisis, along the lines of the Cuban missile crisis, unless we do everything we can to restrain North Korean behaviour."
He said the impending crisis requires all countries to work together to ensure North Korea is never in a position where they can threaten the US, America, Australia or any allies with a nuclear weapon.
During Mr McCain's visit, Australia announced an additional 30 troops will be sent to Afghanistan.
Asked why security in the middle east seemed to get worse, not better, after US intervention, Mr McCain was scathing of former president Barack Obama's approach.
"We have not pursued a strategy for victory. The Obama administration's strategy was' don't lose'," Mr McCain said.
Meanwhile, he believes President Donald Trump's advisors have the capacity to achieve victory.
"I believe that this national security team that is around the President now, General McMaster and General Kelly and General Mattis, I think they are developing a strategy and that strategy means victory," he said.
Mr McCain said Mr Trump accepted the advice of his team "most of the time".
"Can I tell you that he does all the time? No," Mr McCain said. "Can I tell you that it bothers me? Yes, it bothers me."