Political leaders and terror experts warn that Australians with radical views could be drawn to take part in the conflict in Ukraine, potentially posing a security risk if they return home.
The Department of Home Affairs and spy agency ASIO have both said they monitor those travelling to join the conflict in the region, which has already drawn thousands of foreign fighters — including a small number of Australians — since 2014.
It is feared Russia's invasion could spark renewed global interest in joining the fight and Australian laws may not prevent extremists from travelling to take part and then returning home.
Ukrainian president Volodymyr Zelenskyy has called on "all citizens of the world" to join Ukraine’s defence.
In the past, right-wing and left-wing extremists have been drawn to both sides of the conflict.
Even as their compatriots battle to hold on to their capital, Ukrainians in Australia say they do not want to see ideologically motivated foreigners join the fight.
"If you've got an agenda, then I don't think you're serving anybody's purpose," Stefan Romaniw, co-chair of the Australian Federation of Ukrainian Organisations, told RN Breakfast.
His message to those considering the trip was simple: "Don't."
Ukraine seen as 'front line of a global war'
International relations lecturer Sara Meger has interviewed dozens of combatants in Ukraine, including about 15 foreign fighters.
She said the new round of fighting would draw more foreign fighters to the country.
Understanding why non-Ukrainians and non-Russians want to join can be complicated.
One common factor across the battlelines is that many of the foreign fighters have served in their home military, with some having fought in Afghanistan and Iraq.
According to Dr Meger, some past fighters missed being in combat but ended up leaving Ukraine quickly, bored with the bogged-down, slow-burning clashes that preceded the latest invasion.
Others travel for more complicated ideological reasons.
"It's not just the David and Goliath story of defending Ukraine, but seeing this as the front line of a global war," she told RN Breakfast.
As part of her research, she asked foreign fighters whom they saw as their enemy.
"Which I thought was quite telling because I expected him to say 'Russians' or 'separatists', but they really view it through this ideological lens."
She said the idea of fighting against Russia in Ukraine had picked up steam in far-right spaces online.
"One guy I spoke with, he was a bit of a war adventurer. It wasn't so much Ukraine he was interested in," she said.
"But when he said he was tossing up between going either to Syria to fight against ISIS or Ukraine, it was the whiteness of Ukrainians that led him there."
More returning fighters a risk
In 2018, an ABC investigation named two Australians who joined the conflict, including one former Neo-Nazi.
There is no evidence either currently poses a threat in Australia.
But intelligence services, Australian Border Force and terror researchers are afraid others who join the conflict might pose a risk.
Levi West, director of terrorism studies at Charles Sturt University, said about nine Australians were publicly known to have travelled to the front lines of the Ukraine-Russia conflict in the past, mostly to join the Ukrainian side.
"The risk lies in the idea you go over, you experience conflict, you experience violence, you get trained, your capability improves," Mr West told RN Breakfast.
"It means when you return, you have two things.
He said there was not any evidence that yet another round of fighters was leaving to join the conflict, but militias on both sides were already producing recruitment propaganda.
ASIO director-general Mike Burgess recently told journalists his organisation was "well versed in concern" about foreign fighters and would be "watching that closely".
A spokesperson for the Department of Home Affairs said in a statement that Australian law prohibited Australian citizens and residents from engaging in hostile activities overseas unless they were serving in the armed forces of a foreign country.
"The Australian government is alert to the potential for Australians to travel to Ukraine to engage in hostilities and will continue to monitor and assess movements of individuals from Australia and apply policy and operational mitigations where necessary," the spokesperson said.
Concern Ukraine fighters 'not on the radar'
That exemption for fighters joining the armed services of a foreign country has led to concerns that authorities may not be able to stop people taking part in the conflict then returning home.
Some former paramilitary groups associated with the far right in Ukraine, which have attracted foreign fighters, have been integrated into the mainstream Ukrainian army.
Labor MP and violent extremism expert Anne Aly told RN Breakfast that Australia's foreign fighter laws were drafted in response to those who were taking up arms for the so-called Islamic State group.
"We've had people in the past go over and fight in Ukraine," she said.
Dr Aly is also a member of the powerful Parliamentary Joint Standing Committee on Intelligence and Security.
She is concerned Australia does not have a comprehensive system in place to monitor and reintegrate fighters who do return home.
"The way we dealt with a lot of foreign fighters going to fight with ISIS was through instruments such as cancellation of Australian passports," she said.
"We didn't have a lot of foreign fighters return."
"Other nations who did have a lot of foreign fighters return put programs and processes in place to monitor, to reintegrate or rehabilitate those foreign fighters."
Dr Aly would like to see the government work across party lines and with experts to assess the scale of the risk now posed.
