Residents fleeing the Kiev suburb of Bucha reported Chechens machine-gunning cars, even those with the word ‘children’written in their windscreens. The arrival of Chechen strongman Ramzan Kadyrov, who claims to lead a force of 10,000 of his countrymen, will have unnerved Ukrainian volunteers defending their city. When the Chechens intervened in eastern Ukraine in 2014, they gained a reputation for undue cruelty. ‘There were stories of Kadyrov’s guys castrating prisoners of war,’ one woman with family still living in the Donbas told me.

Ukrainian fighters won’t be the only ones feeling nervous. Russia’s military has had an acrimonious relationship with the Chechen leader stretching back nearly two decades. I first met the ‘Kadyrovtsy’– Kadyrov’s fearsome cadre of fighters ­­–­ during the second Chechen war in 2003. Embedded with Russian Spetsnaz special forces, I was riding in an armoured personnel carrier outside the Chechen capital Grozny. Around me, weighed down by heavy-duty flak jackets and olive green titanium helmets was a combat patrol group.

In front of us lay the cratered and shell-spattered remains of a makeshift checkpoint. The soldiers around me each fed a bullet into the breech, pulling down their metal face guards and clicking them into place. Two sleek-nosed helicopter gunships hummed low overhead. The commander of our patrol group was nicknamed Mokry. The soldiers leapt from the vehicle as he barked an order, running for the cover of the surrounding scrub. There they lay or knelt, fingers on triggers. Two hundred yards away a white Lada rolled to a halt.

‘That’s them – the Kadyrovtsy,’ Mokry said. ‘They are supposed to be our allies but if we so much as blink, they’ll fuck us up.’ The men in the Soviet vehicle were, in the eyes of many Chechens, turncoats. During the first Chechen war, between 1994 and 1996, they fought against the Russian army as part of a national resistance that left an estimated 5,700 Russian soldiers dead.

But when Putin came to power in 2000, the group then led by Ramzan’s father Akhmad Kadyrov went over to the Kremlin. Financed by Moscow and backed up by the firepower of the Russian army, they took on rival Chechen clans, eliminating them one by one. But they also began to edge out the Russian military and the FSB, Moscow’s powerful intelligence agency.

Even though the Kadyrovtsy were now blessed by Putin, the Russian military never forgot that they had once slaughtered their comrades. They resented their special status and generous funding from Moscow. ‘If they so much as twitch a muscle, shoot the fucking lot of them,’ the Spetsnaz commander told his men that morning as we set out on the patrol. It took years to crush his opponents but today Ramzan, who is still only 45, has unrivalled power in Chechnya. He runs the most oppressive regional regime in Russia, persecuting and killing political opponents, human rights advocates, and homosexuals.

Not long after my first meeting with the Kadyrovtsy, I drove to the tiny village of Tsenteroi in central Chechnya to interview Akhmad, Ramzan’s father, at his home. We sat without aides, bodyguards or translators. Akhmad was a gruff man and exuded a sense of violence. I asked him about accusations that his men were kidnapping and killing opponents. ‘Abductions happen,’ he conceded. ‘But there are many bandits who pretend to be my bodyguards. Anyone can forge an ID card.’

Ramzan Kadyrov following in his father Akhmad’s footsteps (Getty)

A few weeks later Akhmad was killed by a car bomb. I returned to Tsenteroi as many dozen Chechen tribal leaders came to offer their condolences. I was the only foreigner there.Kadyrov senior was probably killed by Chechen rebels. But rumours swirled that the FSB or Russian military had had a hand too.

A few days later Ramzan, then only 27 and obviously bereft, flew to Moscow. Wearing a tracksuit, he was comforted by Putin and anointed to lead in his father’s stead. In the intervening years, Kadyrov rebuilt Grozny in his own image – garish, flashy, overtly Islamic. He is rumoured to have been behind the killing of a number of Russian opposition figures, including the journalist Anna Politkovskaya and the political leader Boris Nemtsov. Kadyrov has never hidden the fact that his first, perhaps only, loyalty is to the man in the Kremlin. This week he referred to himself as Putin’s foot-soldier.

Soon after the Ukrainian invasion, Chechen social media was filled with comments condemning Kadyrov’s role. Naturally they were swiftly removed by the censors. But if Kadyrov has critics at home, he also has enemies abroad – and not just on the Ukrainian side. Putin may be urging him on, but there are still plenty of Russians who would be pleased to see the Chechen warlord killed.

Julius Strauss runs the newsletter Back to the Front about Russia, Ukraine, Afghanistan and the Balkans.