The world has witnessed a number of right-wing extremist attacks this year, and a former director of America's National Counterterrorism Centre fears there will be more.

Key points: Mr Rasmussen says the US could learn from Australia on gun controls

Mr Rasmussen says the US could learn from Australia on gun controls He cautioned against blaming mental health as key reason for attacks

He cautioned against blaming mental health as key reason for attacks Political rhetoric in the US is "unhelpful" when addressing right wing extremism

Nick Rasmussen, who served under both Barack Obama and current President Donald Trump, has warned that right-wing extremism is becoming more prevalent.

"It is certainly the experience we are having in the United States right now and there are signs that this is happening in other countries," he told AM.

"Individuals who share these views, whether they are tied to white supremacy or anti-Semitism or some other hate-based ideology, are finding each other across the globe."

Mr Rasmussen is visiting the Australian National University's National Security College to talk on a range of issues including terrorism, and said the threat of right-wing extremist attacks was just as high as the threat of an attack by Islamic extremists.

"I think there is a certain equality in the United States, at least in terms of case load," he said.

"Even though the horrific attacks tied to domestic terrorism have received more press attention in recent weeks, not too many weeks go by in the United States where there isn't an arrest of an individual for terrorism-related activity related to ISIS or Al Qaeda."

ASIO boss Duncan Lewis has previously confirmed that intelligence agencies are keeping an eye on right-wing extremism in Australia.

Asked about the threat during Senate Estimates in October last year, Mr Lewis said the problem was "coming off a very low base" but certainly re-emerging.

"I wouldn't say that it's a lot worse; they're probably a little bit better organised than they have been in the past, but we are monitoring this very, very closely," Mr Lewis said.

Mr Rasmussen said it was hard to judge the potential volume of right-wing terrorists in Australia, but pointed to what he described as a critical difference with the US.

"Australia has managed its gun control concerns much more effectively than the United States has, in my opinion," he said.

"Individuals who are so motivated in the United States don't have much difficulty in acquiring high-powered weapons of war and thus they can inflict horrible violence in a brief period of time."

What motivates far right extremism?

The El Paso gunman was linked to a racist, anti-immigrant screed posted online shortly before the shooting. ( AFP: photo courtesy of KTSM 9 )

Following the El Paso and Ohio shootings, President Donald Trump declared that mental illness was a contributing factor to the attacks.

Mr Rasmussen said that may be true in some instances, but he has cautioned against using mental health as a "deflection".

"It is simply a denial of the fact that it is hateful rhetoric and hateful ideologies that underpin these attacks," he said.

"I wouldn't want to suggest that a better mental health system somehow solves this problem, that simply isn't the case."

Mr Rasmussen pointed to political rhetoric in the US as also being unhelpful.

"It would be a good thing if the President and indeed all political actors in the United States would find ways to moderate their rhetoric and not contribute to the sense of social divide we have right now," he said.

"[But] in the end, I think, most of the solutions that hold some promise in terms of dealing with any form of extremism, most of those solutions end up being community-based rather than government-imposed."