Images of protesters brandishing hangman's nooses in Melbourne while demanding the shooting assassination of Victoria's Premier has rightly startled most Australians and drawn widespread condemnation.

The recent ugly scenes in the world's most locked down city have been shocking, but for intelligence agencies who monitor various security threats to the country, they are neither surprising nor unexpected.

Months of lockdown has fomented a feeling of resentment and anger in the city once described as the world's "most liveable".

ASIO boss Mike Burgess saw it coming back in March.

Earlier this year, the director-general of security declared "COVID has reinforced extremist beliefs and narratives about societal collapse". 

"Extreme right-wing propaganda used COVID to portray governments as oppressors, and globalisation, multiculturalism and democracy as flawed and failing," he said at the time.

"We are seeing a growing number of individuals and groups that don't fit on the left-right spectrum at all.

"Instead, they're motivated by a fear of societal collapse or a specific social or economic grievance or conspiracy."

The ASIO boss also painted a picture of today's ideological extremist, someone who is more likely to be motivated by a social or economic grievance than national socialism, for instance.

"More often than not, they are young, well-educated, articulate, and middle class – and not easily identified," he said.

However, placing labels on those considered to be "ideological extremists" at recent protests is no longer a simple task. 

As one senior intelligence official puts it, "yes, right-wing extremists are attending and are involved in the protests – but it is wider than that". 

"For some time, we have been predicting a concerning growth in issue motivated violent extremism," the high-ranking operative told the ABC.

In many ways, international experience has helped prepare Australian authorities for what could occur here. 

So far, mercifully, those extremist threats have not resulted in recent loss of life on Australian streets.