(Bloomberg) -- The “Spider” is not your ordinary Ukrainian soldier. He’s one of the thousands of irregulars who played an important if controversial role when conflict broke out nearly eight years ago and could do so again, if Russia decides to escalate.

A former kickboxer who says he spent 16 years in prison for “robbing factory bosses” in the 1990s, Ruslan Pustovoit served in the regular army as a decorated intelligence officer. He ran operations behind enemy lines. 

But the 52-year-old also formed a militia unit to fight in 2014, when the decaying armed forces were unable to resist Russia-backed separatists in Ukraine’s eastern Donbas region. In 2017 he was named a “People’s Hero of Ukraine.”

Now Pavuk —  Ukrainian for spider — is again commanding irregulars. “Officially there are no volunteer battalions at the front lines. But we are volunteers and we work with the 35th Brigade in Shyrokyne,” said Pavuk, referring to the small beach town just outside the city of Mariupol that is a daily battlefield.

With more than 100,000 Russian troops massed on the border and warnings of a wider war growing daily, Ukraine’s military, while much improved, remains outmatched by Russia’s. That’s despite the rush of defensive weapons being flown in by the U.S, U.K. and others.

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“Now we have 250,000 troops in the regular army, but it will not be enough to man the front and at the same time keep forces back to secure interior parts of Ukraine,” said Alexander Kovalenko, an Odessa-based military and political analyst for InfoResist, a website. 

Experienced fighters from the paramilitary groups that flourished early in the war with the Kremlin-backed separatists could be important for any partisan-style campaign against the Russian military, Kovalenko said. “They’re a resource and they want to fight. Why would you not use them?” he said. 

Officials in Moscow say they have no plans to invade, but that they would respond to any Ukrainian attempt to take back its eastern territories. Ukraine has never said it would try and regain them force.

Ukraine has a long history of organizing volunteers into an effective military, starting with Cossacks, who formed a formidable force in the 15th to 17th centuries. Kovalenko estimates there are 50,000 to 60,000 such fighters now in uniform, although exact numbers are hard to assess. 

Some former militias are again training up reserves, as ordinary Ukrainians come forward. Regional governments are organizing territorial defense forces. It’s unclear how well armed or trained they would be if called on to fight. 

The government has placed volunteer militias under the National Guard in an effort to impose control. The National Guard didn’t immediately respond to a request for comment. 

Putin’s Troops Wouldn’t Get Cheers in This Once Pro-Russia City

A 2017 post on the website of the Main Intelligence Directorate of the Defense Ministry confirms Pavuk’s account of his military service, describing two times he was severely wounded. 

Pavuk’s award wasn’t the Hero of Ukraine order given out by the president (although the state also recognized him in 2017 for courage). It was a parallel decoration aimed at irregulars.

Some early militias gave fuel to Russian propaganda, which continues to portray Ukraine’s leadership as fascist. The Azov Battalion, with its now infamous insignia similar to the Nazi-appropriated “Wolfsangel”, attracted White supremacists to its ranks. The U.S. Congress banned the provision of weapons to the Azov Battalion in a 2018 spending bill, despite its inclusion in the National Guard. The battalion is today spread over bases along a 50 mile (80 kilometer) bay in Ukraine’s southeastern corner.

In an interview, Pavuk expressed no right-wing views. In what he called an ironic gesture to ridicule such suggestions, he keeps a Nazi German officer’s hat on a hook behind the door. 

Mid-conversation, some of his men entered the apartment, scuffing their boots on the Russian flag that serves as a doormat and stacking Kalashnikovs in a corner. Pavuk said they were back from the front.

News that the U.K. has begun deliveries of light anti-tank weapons has caused particular excitement, because they can be used effectively in urban warfare. That could significantly increase the risk to Russia of using tanks or armored personnel carriers in any attempt to capture cities, in the event of a wider war. 

Angered by what he calls a failure of state authorities to actively prepare a stay-behind partisan force should Russian troops take Mariupol, Pavuk says he has built his own group to sabotage supply lines around a core of 70 veterans.

“Life in the city goes on. They’re building new parks and new buildings and all that,” says Pavuk. “But we’re organizing the city’s veterans.”

While part of that is perhaps bravado, he and some of his men have fought in Ukraine’s grinding conflict for close to eight years and it’s difficult to see why they would stop.

Less clear is whether they could again make a difference, in the very different kind of fighting that would be involved in an open war with one of world’s most powerful militaries.

©2022 Bloomberg L.P.