As the Islamic State group seems to crumble across Syria, a top Russian commander points to a pulverised tank once used by the jihadists as proof of his country's essential role in their demise.

In recent months, Syrian troops have rolled IS back in the country's northern province of Aleppo, Hama and Homs in the centre, and most recently, Deir Ezzor in the east.

But Moscow is keen to remind the world that its support for Syria's beleaguered forces made these advances possible.

In Uqayribat, a town recently recaptured from IS, the chief of staff of Russia's contingent in Syria leads a tour of a ruined factory where IS once produced one of its most terrifying weapons: "tank-bombs."

Jihadists would pack anti-tank mines and TNT into the vehicles, retrofit them with protective armour, then detonate them at Syrian army positions.

"The effect of such kamikaze tanks is considerable," says Lieutenant-General Alexander Lapin during a tightly-controlled tour by Russia's military.

He points proudly to the gutted shell of an old Soviet tank, likely captured from government forces when IS swept through central Syria.

Ironically, it was a Russian strike that reduced the would-be bomb -- with a "kill zone" of 300 metres (yards) -- to a harmless, charred carcass.

"Such design lets the tank lead both offensive and defensive actions. IS was the first organisation in history to use such a weapon," he says.

"Only Russian aviation can destroy them with their bombs."

- 'Kamikaze tanks' -

Uqayribat sits in the vast desert territory of Syria's central Hama province and has changed hands several times between jihadists and government troops in Syria's six-year war.

In the first press tour to the town, Lapin says Syria's army and a volunteer brigade ousted IS from Uqayribat, but Russia also played a key role.

"New methods of warfare were used here, and Russian aviation inflicted extensive fire damage here," he adds.

Weapons including Russia's OFAB-500 fragmentation bombs have shattered 48 tanks in Uqayribat -- 30 percent of which were being fashioned into "kamikaze tanks."

Moscow has found three tank factories like the one in Uqayribat, and suspects one is still operating in Al-Mayadeen, an IS bastion near the border with Iraq.

"We will find it, and we will destroy it," Lapin says.

Russian reconnaissance drones were the first to scout the Uqayribat factory, and they also uncovered a network of IS tunnels criss-crossing the town.

"The underground town is a network of tunnels from 100 to 700 metres linked by passages which allowed them to move resources from one side of the town to another," Lapin says.

"All of these tunnels were discovered by Russian aviation's drones."

Moscow's military intervention in Syria began in September 2015 with an air war that helped troops loyal to President Bashar al-Assad recapture swathes of strategic territory.

"Wherever the Russians decide to apply their military capability, the regime can win," says Jeff White, military analyst at the Washington Institute for Near East Policy.

"Their broadest strategic goal is reassertion of Russia as a major player in the region and in the world."

- 'Extensive work' -

In recent weeks, Russian-backed regime forces have squeezed IS in eastern Deir Ezzor, in an offensive Moscow sees as the final stretch of the six-year war.

"We've done extensive work. The Syrian army became professional and professionalism doesn't happen on its own," says military spokesman Igor Konashenkov.

"I'm certain that everything here (in Syria) is coming to an end."

Russia has played a "leading role" in helping Syria's army regain its offensive capability, according to Moscow-based military analyst Alexander Golts.

"Suddenly after six years of war, the military power of the Syrian army is looking better in the last six months," he says.

But the possibility that Syrian troops could recapture Deir Ezzor on their own remains "from the realm of fantasy," Golts adds.

In addition to air strikes and reconnaissance, Russia has also dispatched special forces, de-mining experts, and military police officers across Syria.

Pavel Felgenhauer, military observer for Novaya Gazeta newspaper, says more than 2,000 military advisers are also on the ground.

"Some two million tonnes of military supplies have been shipped to Syria," he says, including Russian weapons systems like the TOS-1 flamethrower rocket launcher and Msta artillery units.

Looking out over the vast territory that forms Syria's coveted desert region, Lapin says the Russian-backed victory in Uqayribat would be followed by many more.

"We cannot be stopped," he says.