While many foreigners are contemplating a move away from Hong Kong as widespread protests continue to grip the city of 7 million, one Australian expat is joining the fight against Beijing.

Key points: Hong Kong's pro-democracy protesters have rallied for 12 weeks

Hong Kong's pro-democracy protesters have rallied for 12 weeks An Australian finance worker living in Hong Kong has joined their ranks

An Australian finance worker living in Hong Kong has joined their ranks Carrie Lam has warned China may send in troops to 'quell' the movement

The unrest and uncertainty over what protesters might do — or what actions China might take — is leading some within Australia's 100,000-strong expat community to question whether the city is still safe.

But Australian citizen Daniel, who classifies himself as a peaceful middle-class professional, joined the demonstrations in June and has continued to show his support for the movement.

"In Australia we have proper democracy but in Hong Kong, democracy is being slowly eroded away and I'll try to do whatever I can to try and help the cause," he said.

"I've been taking part in most of the rallies and the unlawful assemblies."

The idea of violence as a legitimate form of political expression, hand-in-hand with peaceful protest, is becoming increasingly mainstream in the evolving tactics of a decentralised pro-democracy movement.

"The peaceful protests didn't get anywhere, so people feel they have to take some more extreme measures and I understand that," Daniel said.

He does not believe peaceful protests will get the attention of the Chinese communist party.

"You need something extreme to bring Hong Kong to a standstill, or to destroy Hong Kong's economy for China to say 'we don't want a stake in Hong Kong' and back off," he said.

From finance worker to pro-democracy rebel

Born and raised in Western Australia, the financial sector worker is the same age as the twenty-somethings taking to the streets, allowing him to sympathise with their cause for a democratic future.

Daniel asked the ABC to protect his identity as he regularly travels to mainland China for work. ( ABC News: Robert Koenig-Luck )

Despite having the safety of an Australian passport, the ABC cannot reveal Daniel's full identity, because his support for the movement puts him at risk of being detained when he travels to the mainland for work.

"There are cameras everywhere. If China wants to identify you, it can," he explained.

"Last week there were some police dressing up as protesters and the suspicion is, they are Chinese police. That just adds to the terror that Chinese police are coming down to Hong Kong to clear the protests."

The protesters sport full battle-ready gear of hard hats, gas masks and protective clothing.

Hong Kong's protesters protect themselves with tear gas masks, hard hats for falling objects, and gloves. ( Reuters: Tyrone Sui )

As the ABC followed Daniel at one of the protest rallies, he nervously looked around and frequently glanced up at the surrounding high-rise buildings, telling us there are security cameras capturing our every move.

"These cameras have 5G technology and do facial recognition. The government says it's to monitor traffic, but I think it's a load of bullshit," Daniel said.

"People are covering their faces because they're scared that one day if China does overtake Hong Kong, they'll have to pay for their actions."

Like most protesters, Daniel wears heat resistant gloves in case he has to pick up tear gas canisters. ( ABC News: Kathryn Diss )

Reports have emerged in recent weeks that those crossing the Hong Kong-China border have had their phones checked for materials related to the protests.

"We have heard stories of immigration searching through phones and if they find any anti-Chinese messages, they will lock you up and even take you to one of those brainwashing detention camps," he said.

Youth-led movement becomes increasingly sophisticated

For 12 weeks, tens of thousands of protesters, mainly university students and young professionals, have taken to the streets — sometimes violently — to fight for their future.

Their actions have become increasingly aggressive and disruptive as they have tried to choke the financial hub's economic prosperity.

It has further angered Beijing, which has now threatened to use force if required to quell the protests and has stationed paramilitary troops at the border in Shenzhen.

"If they bring Hong Kong to a standstill they may well have more leverage for the government to give in to one or two demands," Daniel said.

The stamina and intensity of the movement, which claims to be "leaderless", has surprised many.

The strategy of the protest has evolved into a well-coordinated movement, which uses encrypted messaging apps like Telegram to quickly spread instructions to demonstrators.

The occupation of Hong Kong Airport reportedly took half an hour to organise. ( ABC News: Thomas Peter )

The ABC was told the effort to mobilise people for the airport sit-in, which led to the cancellation of hundreds of flights, garnered 30,000 followers within just 30 minutes.

"It's a leaderless movement, but it is very well organised, and they have an aim and they will execute their aim very quickly and then leave," Daniel said.

In June, the protesters moved together as one group, but they have now splintered into smaller cells.

"Everyone will gather in one place and then it splinters into 10 or 20 groups and move with different objectives to stretch police resources," he said.

Another masked Hong Kong protester, who went to university in Perth, said he held little hope the movement would achieve anything, but felt compelled to show support.

This young protester told the ABC he'd like to move to Australia rather than remain in Hong Kong. ( ABC News: Kathryn Diss )

"I have worked in China for a year and I understand how the China government treat their people. [They] brainwash them, limit the news, they use government power to control their citizens," he said.

"I think I'll move to another place in the future, to maybe Australia or Britain where they have a fair government. I want to live in a place that's democratic, full medical system, education system."