Ukraine's 'secret weapons': Inside the training camps for foreign fighters

They aren't there because their homelands sent them into battle – they chose to come because standing by and doing nothing simply wasn't an option.

"I have to be here because if we don't stop Russian aggression here, it can lead to other places," Harrison Jozefowicz told reporter Mark Burrows.

The former US Army soldier quit his job as a Chicago police officer to take up arms halfway across the world because he felt his skills were needed to prevent further catastrophe.

"I don't want to see the same thing happen in my own backyard," he said.

He joined a 20,000-strong volunteer army of soldiers from 52 countries, stepping up where NATO troops have so far refused to tread to avoid escalating tensions.

It's an incredibly brave and incredibly dangerous decision, even more so with Russians targeting anywhere they believe is being used as a base or training location.

As a result, the camp q visited was shrouded in secrecy – reporter Mark Burrows and his crew were guided there by two European men who didn't tell them where they'd be going.

The confidentiality only intensified once they arrived at the sand-bagged military training centre, where some soldiers hid their faces from our cameras.

They may have been scared to reveal their identities, but they clearly didn't fear the frontline – and killing if necessary.

While some might consider that crazy, Mamuka Mamulashvili, the Georgian National Legion commander who helps run the training camp, thought otherwise.

"It is not mad, it is normal for every human being," he said.

"Everybody agrees this is the only place in the world where they can defend freedom today."

He revealed a few Australian volunteers have come to the camp, despite it being technically illegal in our country thanks to a law originally passed to stop Australians going to fight for ISIS.

"They all want to be part of the history, to defend freedom and defend democracy," he said.

In just over an hour at the camp, the 60 Minutes crew saw more than 100 fresh recruits preparing for combat – learning how to use weapons, defend against tanks, avoid landmines and more.

Harrison Jozefowicz described the atmosphere as "surreal", knowing that soon they would be laying their lives on the line for millions of strangers.

"The Ukraine people are crying out for help and somebody has to come and help them," he told Mark Burrows.

He had faith that his growing band of brothers and sisters from around the world will be able to turn the tide against the invaders, and just like David before them, topple the Goliath of Russia.

"The more the merrier … eventually we will start making a big difference," he said confidently.

"The Russians aren't going to know what hit 'em."