With estimates of up to 11,000 foreign fighters in Syria, Western powers are increasingly worried about the potential national security threat posed by returning fighters.

But in a country more than 14,000 kilometres from the frontline, Syria's civil war is also playing out in Australia's suburbs, with numerous beatings, assaults, shootings and property damage being reported along sectarian lines.

At the heart of the violence, which has predominantly been in Australia's two most populous cities, Sydney and Melbourne, are those for and against the Syrian government of President Bashar al-Assad.

More than 15 incidents of violence involving members of the Lebanese, Turkish and Syrian communities have been reported.

However, Andrew Zammit, from the Global Terrorism Research Centre at Monash University, who has kept a tally of these cases, told Al Jazeera that Syria-related violence in Australia had actually decreased in 2013, compared with the previous year.

The situation in Syria, with the potential for violence spilling into other parts of the Middle East, increases the possibility of associated communal violence in Australia and remains a concern. - Australian Security Intelligence Organisation

Despite this, local violence, along with a number of citizens who have joined the insurgency, has the Australian government concerned about its own national security.

Last year the Australian Security Intelligence Organisation (ASIO) acknowledged the tensions in its annual report:

"The situation in Syria, with the potential for violence spilling into other parts of the Middle East, increases the possibility of associated communal violence in Australia and remains a concern for ASIO."

Australian fighters

While there is no exact figure on the number of Australians who have gone to Syria, rough estimates suggest about 200 have fought in the nearly three-year war that has seen more than 130,000 people killed.

About 100 Australian fighters are still active there, according to David Malet, associate director of the Melbourne School of Government.

"Only a half dozen have been reported killed, so if these numbers are accurate many have already returned, or else they have gone on to be foreign fighters in Iraq or elsewhere," Malet, who recently published a book about recruits of overseas insurgencies, told Al Jazeera.

Observers say Australia's large Lebanese community with ties to the region, which enabled volunteers' movements in and around Syria, was a likely explanation for the presence.

"Lebanese Australians have also previously been foreign fighters in Lebanon and Somalia, and involved in domestic terror plots in Sydney, so there are no doubt active connections to some of the armed groups in Syria," said Malet.

However, he noted there was no evidence that other countries with large Lebanese communities were sending large numbers of foreign fighters, like Australia was reportedly doing.

"The explanation probably lies with the effectiveness of the recruitment networks within Australia and their contacts in Turkey and Lebanon who help facilitate entry," he said.

"Foreign fighters volunteer when effective recruiters tell them that they are part of a global group that is under extreme threat, and that they have a duty to intervene because no government is doing the right thing."

Zaky Mallah, who was the first person to be charged and acquitted under Australia's anti-terrorism laws, and who has deep ties to Syria, said dual Australian-Lebanese citizens were drawn to the conflict because of their disenchantment with life in Australia.

"The majority of Australians heading to Syria are from Lebanese backgrounds. The Lebanese youth here feel disadvantaged, isolated and discriminated against. Many [are] unemployed and have turned to religion as a result," Mallah said.

"Many Lebanese youth have turned to Salafi ideology because it is strong and helpful to counter the struggles of life here in Australia. Many Australian Lebanese youth will find themselves ideologically 'connected' with these groups."

Government concerns

In light of the recent death of a couple from western Sydney in Syria - and in a bid to deter more Australians from going to the war-torn nation - the government has stepped up its rhetoric.

Immigration Minister Scott Morrison signalled that those who fight in Syria could be at risk of losing their citizenship, while the Australian Federal Police have said anyone returning from fighting there would be treated as a national security threat.

The government has also stepped up prosecutions and ASIO has continued to confiscate the passports of anyone suspected of travelling to engage in "politically motivated violence".

It confiscated 18 passports from mid-2012 to mid-2013, the largest number in any given year-long period.

Joseph Wakim, former Victoria Multicultural Affairs Commissioner and founder of the Australian Arabic Council, said the new government was taking a harder line than the previous one.

"The new coalition government has been critical of both sides and sympathetic to the Christian minorities who have been targeted by the anti-Assad forces," he told Al Jazeera.

"With Australia's suite of anti-terror laws, and concerted efforts by our intelligence agencies to share resources and establish strategic community contacts, Australia's buffer against terrorist acts has been bolstered. Local community elders and clerics have also been more vigilant and public in encouraging good citizenship and close cooperation with authorities, including denouncing potential terrorists."

Real threat?

Despite this, the government continues to voice its concerns that the experience, new skills, ideologies and connections formed on Syria's battlefield could see the fighters posing a threat to Australia when they return.

Given their susceptibility and obedience, I suspect that local networks are already in place for the waging of local attacks against anyone who represents their infidel enemy. - Joseph Wakim, Australian Arabic Council

But are its concerns warranted?

Last February, Norwegian terrorism expert Thomas Hegghammer released a report showing that one in nine Westerners who fight in foreign jihadist insurgencies ends up becoming involved in terrorist plots back home.

Malet said research on foreign fighters was still a new field, adding different studies produced differing conclusions about the likelihood of "blowback" from returning foreign fighters.

"Other studies show that most foreign fighters simply resume their previous lives so long as they are provided amnesty," he said.

"However in 2009, four Australian citizens returning from Somalia were arrested plotting to attack the Holsworthy Army barracks, so there is precedent for the Australian government to be concerned."

Wakim said Australians fighting in Syria were driven by their perceived moral duty to aid their Muslim brothers to "rid Syria of an infidel secular authoritarian regime and replace it with one that upholds their brand version of pure Islam".

"While there is no evidence of such individuals planning attacks in Australia, their recruitment activities tap into a population of Australian-born and disengaged youth searching for a worthy cause - and at times martyrdom," he added.

"Given their susceptibility and obedience, I suspect that local networks are already in place for the waging of local attacks against anyone who represents their infidel enemy."

Zammit echoed his concerns. "[An attack] is a real possibility, based on our past history and on the experience of other Western countries."

But despite government attempts to deter people from going to Syria, some say that nothing will stop them.

"If a Muslim's ideology is strong, then imprisonment means nothing - no deterrent. He or she would rather stay in Syria until martyrdom," Mallah told Al Jazeera. "[It is] not worth coming back to jail."

Follow Sophie Cousins on Twitter: @SophCousins