Pro-Russian rebels carry a coffin with the body of their commander Aleksey Mozgovoy during a funeral in Alchevsk in May 2015. Photo by Alexander Ermochenko/EPA

The rebel commander had been married for less than 24 hours before the car bomb exploded. Pavel Dryomov, one of the most prominent, pro-Russian separatists in eastern Ukraine, was celebrating his wedding in the rebel-held town of Stakhanov with his new wife and a colorful array of guests, including men drawn from the ranks of his own Cossack militia. A former bricklayer in his late 30s, the outspoken commander appeared to have finally made peace with his notional superiors in the rebel leadership; the nearby stretch of the front was relatively quiet and an upcoming Christmas truce promised to calm hostilities further. There seemed no better time for a celebration.

On the morning of December 12, Dryomov and his driver left the all-night wedding party in Stakhanov to head northwes­t to the devastated frontline town of Pervomaisk. In a wintry corner of Ukraine's rebel heartland, the potholed highway carved through rolling, snow-covered steppe beneath a horizon stained by the occasional smokestack and a pair of industrial behemoths – a coke furnace and vast steel works. With frontline trenches invisible at this distance, any traveler would be forgiven for thinking that peace had finally returned to this swathe of Ukraine's eastern rustbelt.

But Dryomov would never reach his destination. A bomb hidden in his vehicle was detonated as he approached the town's outer limits. The explosion killed him on the spot; his driver died on the way to hospital.

The assassination was the latest in a string of bloody murders of maverick rebel commanders in Ukraine's restive east, fuelling fears among senior separatist ranks of further purges. Rival factions are jostling for power as two opposing camps in the rebels' self-proclaimed Luhansk People's Republic (LNR) struggle to consolidate their rule. In exclusive interviews with VICE News, against a disturbing backdrop of Soviet-style paranoia, illegal detentions, torture and extrajudicial killings, rebel military chiefs and well-placed sources in the regime have spoken of their profound sense of unease — and their fears about who could be next.

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In many ways, Dryomov's demise was a death foretold. It was no secret that the outspoken field commander loathed LNR's Moscow-anointed leadership. The Soviet idealist — some would say warlord — took regular swipes at his superiors and had envisioned building his own neo-socialist "Cossack" republic centered in the depressed mining town of Stakhanov. His units of Don Cossacks — a martial tribe whose medieval forebears fled serfdom to live as free men on the frontiers of imperial Russia — were among the most outspoken militias in their opposition against the LNR's ruling authorities.

In a coarse, rambling video posted on YouTube last winter, Dryomov claimed to possess digital files which allegedly proved corrupt links between organized crime networks and Igor Plotnitsky, the LNR's authoritarian leader. He had gambled on the hope that the contents of this flashcard would serve him as collateral. If he were targeted, he warned, the information would be sent "to every computer server in the world." In the words of a high-level source in the SBU (Ukraine's security service): "Dryomov was neither a comfortable figure for Plotnitsky nor Russian security forces."

However in recent months Dryomov's barbed criticisms had softened after he made peace with Plotnitsky, at least publicly. This truce had no doubt been prompted, in part, by a suspicious pattern of events. He was well aware of the fate of other independent rebel warlords who had refused to submit to LNR's central leadership. They now lay six feet under, permanently silenced.

'This is not the first murder in the LNR of commanders who have distinguished themselves by the independence of their views'

There was Prapor, a pro-Russia, Cossack leader who was killed during an operation by the LNR authorities to disarm his independent militia. Alexander Bednov, a well-known field commander who went by the nom de guerre "Batman," died under suspicious circumstances on New Year's Day, 2015. That same month, Yevgeny Ishchenko — one of Dryomov's allies and the former "people's mayor" of Pervomaisk, the frontline town held by Cossack rebels — threatened to "turn his weapons in the opposite direction," a blatant declaration of his hostility to Plotnitsky's regime. A few weeks later, he was dead.

Perhaps the most high-profile figure to be eliminated in this bloody process of streamlining was Aleksey Mozgovoy, the founder of the pro-Russia "Ghost Brigade." This ruthless commander, known for his love of poetry and distrust of Plotnitsky, showed a diehard devotion to the dream of building a pan-Slavic "Novorossiya" (a historical term, now denoting the loose confederation of rebel-held territory). He was building his own legend, his own fiefdom. And then, in May, he was dead. A roadside ambush of mines and machine-guns killed him, along with six others.

Officially, the LNR authorities blamed subversive Ukrainian groups for the string of mysterious deaths. Privately, many here feel the enemy is closer to home. In the wake of Dryomov's murder, Plotnitsky reportedly outlawed all public meetings of the slain commander's Cossack militants.

In an uncharacteristically provocative piece in December, Russia's official armed forces daily wrote: "Independent observers note this is not the first murder in the LNR of commanders who have distinguished themselves by the independence of their views."

That same month, Alexander Zhuchkovsky, an influential, pro-separatist activist and blogger, alleged that responsibility lay even higher than the LNR. Senior separatists, he wrote, "cannot take that level of decision" — a thinly-veiled allegation of Moscow's involvement in Dryomov's death. Amid indications that the Kremlin is serious about de-escalation, rebel field commanders who resist any rapprochement with Ukraine are put out of commission.

'Plotnitsky is becoming paranoid.... I could be next'

Now, senior paramilitary figures operating around Luhansk fear they will be next to slip into the crosshairs. Alexey Markov rose to the position of second-in-command in the Ghost Brigade after Mozgovoy's murder. He told VICE News that he was "confident" the LNR leadership had no hand in Dryomov's murder, instead blaming "criminal elements or Ukrainian saboteurs."

"We are really sad to lose our friend and comrade but we try not make hasty assumptions," Markov said, adding: "Anyway, we are the last independent division, and we know who can be next."

Alexey Markov told VICE News fears he could be next to slip into the crosshairs. (Photo by Pierre Crom) Markov is also in the right foreground in the photograph at the top of the page.

The leader of another paramilitary group, who spoke to VICE News on condition of anonymity due to security concerns, accused the LNR leadership of succumbing to increasing paranoia and said that his unit had come under pressure to disarm. "We are valued by the people but the situation can change at any moment," he said. "Plotnitsky is becoming paranoid and could label us an unofficial terrorist organization. I could be next after Dryomov."

In the wake of December's hit on the Cossack rebel commander, the LNR said it would launch an investigation, understood to be a joint inquiry between the Luhansk prosecutor's office and the local police force in Stakhanov. The mysterious assassination of Mozgovoy had resulted in a similar probe, though many doubt that the investigation will ever be concluded, let alone have its sensitive findings made public. Similar reservations linger in the aftermath of Dryomov's death.

'He will only pay tribute to their shadows'

A source inside the LNR's internal affairs ministry dismissed the rebels' investigation as "bogus." "No one honestly expects to get an answer," said the source, who asked not to be named. "Officially, the suspects range from Ukrainian special ops personnel to criminal groups in Stakhanov. They could even be connected with an inner Cossack struggle. But make your own mind up: who is the most paranoid about losing his throne in LNR? Our leader will trot out all the right words but the investigation will be a whitewash."

A second, mid-level source inside the LNR's security service gave an even more scathing appraisal. "Plotnitsky has no need for charismatic military leaders," the source told VICE News. "He will only pay tribute to their shadows."

The LNR increasingly bears the hallmarks of an authoritarian surveillance-state. A purportedly official document circulating on Russian social media named suspected dissidents within the LNR. (Although it remains unsubstantiated, separate rebel sources later told VICE News that the internal report was genuine and said that two officials had been fired for leaking it.) Alongside each individual's name and job, were two notes: firstly, how they could undermine the regime, and secondly, how to "minimize" the threat they posed.

'The text simply read: 'Exceptional force''

Some were accused of harboring "personal hostility" to Plotnitsky, others were said to have distributed "flyers of negative content" and to have organized rallies against the rebel leadership. Methods of tackling the various threats included "tracking activity on social networks," "monitoring contacts and relationships," engaging them with "advocacy," and subjecting them to investigation by the rebel security services.

The same report also named Dryomov. It warned that his units of armed Cossack fighters had the capability to launch an insurrection against the LNR leadership. It also accused him of speaking "negatively" about his separatist superiors.

On how to reduce this threat, the text simply read: "Exceptional force."

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When war first erupted in eastern Ukraine's Donbass region, few could have envisaged the Russian-backed engineering of rebel pseudo-states that would follow. Although the landmass of the country's breakaway territories is a fraction of the total size of sovereign Ukraine, Moscow has transformed the rebels' ramshackle administrations into regimes that have the semblance of functioning governments.

As part of this process, the Kremlin has reportedly dispatched dozens of trained bureaucrats to support the regimes' staff of amateurs, ideologues and former blue-collar workers — who, according to a recent, authoritative report by the International Crisis Group, are united by their near-total lack of political or administrative experience. Rebel commanders bent on building their own fiefdom have been purged; less diehard candidates have replaced political leaders who defy their Moscow masters with an outmoded narrative of building a pan-Slavic "Novorossiya".

Last September, for example, Andrei Purgin, the imperialist, hardline Speaker of Donetsk's rebel parliament, was kidnapped by Russian security forces. He was held for five days and then replaced by his more conciliatory deputy, Denis Pushilin, a politician known for his unquestioning loyalty to Moscow.

Take a drive through the industrial, Soviet-era city of Luhansk — Plotnisky's urban power base — and the paranoia is palpable. Billboards erected last summer feature the red-star-and-sword emblem of the LNR's security service, the Ministry of State Security (which has the Russian acronym 'MGB,' the same name as Stalin's secret police force). "Citizens, be vigilant," the huge signs urge. "Please report corruption."

The second winter of eastern Ukraine's grinding war looks significantly different from its first. Moscow has shifted its attention to a bombing campaign in Syria to prop up the Assad regime; gone are the large-scale offensives from Russian-backed rebels. Instead, the warring sides have dug into their trenches, firing on each other across no-man's land and engaging in the occasional skirmish. A Christmas truce calmed the renewed wave of rocket and mortar attacks which had erupted at the start of November. However, fighting has since picked up again, Ukrainians face economic collapse, and the war's official death toll has long passed 9,000 lives.

''Somalia Scenario,' 'Little Trojan Horse,' and 'Big Trojan Horse'

Chastened by low oil prices and a sluggish economy, the Kremlin now ostensibly wants to freeze the conflict and has signaled its readiness to implement the Minsk peace accords. However, Moscow can still exploit Ukraine's rebel regions to apply leverage on its smaller, crisis-hit neighbor. Ukraine's security service the SBU envisions three scenarios towards which Russia is working: the so-called "Somalia Scenario," "Little Trojan Horse," and "Big Trojan Horse."

The first, and most extreme, refers to the theoretical Russian aim of reducing a pro-Western Ukraine to a failed state. Oleksandr Tkachuk, the SBU's chief of staff, told VICE News: "This would involve creating political instability, causing the gradual disintegration of government structures, emphasizing different grievances among the population, and disrupting all aspects of political, economic and social life."

Under the "Little Trojan Horse" scenario, rebel-held territories would be re-absorbed into Ukraine's political sphere, allowing them to influence policy in Kiev and block Ukraine from further integration with European and Atlantic structures. Such a veto "could make Ukraine a grey zone between Europe and Russia," said Tkachuk.

"Big Trojan Horse" refers to a restoration of the political regime of former President Viktor Yanukovych, ousted during the Maidan Revolution in 2014. "There is a risk that the pendulum could swing the other way," said Tkachuk. "Some politicians that were close to Yanukovych are still quite active. A proportion of the population sympathizes with these people and there is growing dissatisfaction with current leaders who are unable to deliver what they promised before the revolution. Russia wants to restore these politicians to power and install a regime favorable to the Kremlin."

The International Crisis Group uncovered similar evidence. It carried claims from a number of separatists that their Russian counterparts had cited "a ten-year plan to regain control over Ukraine," combining "continued destabilization of the east" as well as economic and political pressures.

Hundreds of miles from Kiev in Ukraine's far eastern fringes, the creation and consolidation of separatist republics behind the de facto border of an active frontline has spawned powerful factions within the rebel regimes. According to sources in both the SBU and Luhansk's separatist administration, the LNR is broadly split into two rival camps.

On the one side is the bloc of Plotnitsky, who has run the LNR with Russia's backing since mid-2014. On the other, there is the rebel's security service, the MGB, understood to enjoy the backing of several groups: the police force of the LNR; key figures in the rebels' internal affairs ministry; various organizations such as the local chapter of the "Night Wolves" biker gang. Vitaly "The Prosecutor" Kishkinov, the local commander of this pro-Russian motorcycle club, whose members have fought alongside Russian-backed forces, railed against corruption in the LNR regime late last year in a controversial video address that some felt laid the blame with Plotnitsky.

In addition to these two factions are the Cossacks. Despite the recent assassination of their leader, Dryomov, and their gradual incorporation into the LNR's centralized armed forces — the so-called "Luhansk People's Militia" — they remain armed, relatively powerful, and a force to be reckoned with.

Igor Plotnitsky taking oath during his inauguration as new head of the self-proclaimed Luhansk People's Republic in November 2014. (Photo by Yuriy Streltsov/EPA)

Before Ukraine descended into conflict, Plotnitsky was a relatively unknown figure who had served in the Soviet Army then, later, as a lowly official. Despite his pro-Russian fervor, he is reported to have been raised in the small town of Kelmentsi in Ukraine's nationalist heartlands to the west.

But, in April 2014, as separatists in the east began seizing key government buildings, backed by Russian forces and military hardware, Plotnitsky began his rapid ascent. He raised a militant battalion and, a month later, was named the LNR's defense minister. Dour and domineering, with the face of a mafia boss, he became the breakaway republic's ruler three months later. Local opinion on him is split. Some hold Plotnitsky in high-esteem as a hero of the separatist cause; others dismiss him as a despot-in-waiting who profits from a murky network of corruption, criminality and patronage.

In October, the MGB struck at Plotnitsky's inner circle by dispatching security personnel to arrest one of his key allies, the LNR's fuel and energy minister, Dmitry Lyamin. Online footage later showed him at home, handcuffed, bloodied and beaten, surrounded by weapons and large sums of money. He faced a string of charges: corruption, handing control of strategic energy reserves to criminal networks, and selling more than 3.3 million tons of smuggled coal to Ukraine (reputedly around 90 percent of the total amount of coal mined in the rebel enclave).

Illegal smuggling of coal is believed to be one of the most lucrative sources of wealth in the region. Lyamin's dramatic arrest did not just highlight the scale of trafficking around the front line, with the alleged connivance of high-level officials. It also brought into focus the deep factional rifts dividing senior separatists in the LNR. The arrest was widely regarded as a flagrant challenge to Plotnitsky's authority: a statement later released by his office suggested that the MGB had arrested Lyamin without the leadership's approval.

A well-placed source with close ties to senior figures both in the LNR regime and the MGB told VICE News: "The MGB is in direct rivalry with the LNR leadership. Every branch of power is trying to build its own monopoly in terms of economics and influence. Plotnitsky has had his decisions blocked by key figures in the MGB but its head, Leonid Pasechnik, is currently too powerful a figure for Plotnitsky to take down." A senior official in the SBU independently corroborated the claims.

Since October, Lyamin is understood to have languished in a secret jail run by the MGB, beyond the reach of Plotnitsky. "Once he realized that Plotnitsky would not get him out, he started to co-operate with his interrogators," the source added.

A leaked version of a draft report, prepared by the MGB and the LNR's internal affairs ministry, outlines claims allegedly made by Lyamin during his interrogation. The report, which VICE News has seen, suggests that a network of top rebel chiefs and high-ranking Ukrainian officials had joined forces to run a fuel-smuggling cartel operating across the frontline. Lyamin also names a number of Ukrainian fuel companies which, he says, have been granted access to these black market energy supplies.

Some view the report as a means of undermining Plotnitsky's authority without resorting to an actual coup. "The MGB and LNR police don't want to launch a rebellion," the source continued. "The LNR itself is not recognized internationally — such a rebellion would just make them a grey zone within a grey zone. Even Moscow would refuse to deal with them. So, instead, they've started investigating allies of the leadership to turn the screw on Plotnitsky. Opposition groups in powerful LNR circles want him out. The trouble, however, is that Plotnitsky has so far had the backing of the Kremlin."

''Accidental rulers,' guided 'by mixed motives''

Lyamin is not the only senior separatist to lose power amid the shifting sands of the rebel-held east. At the end of December last year, the LNR's Prime Minister, Gennady Tsypkalov, unexpectedly resigned from his post, despite enjoying support from the Kremlin. Insiders say Plotnitsky played a leading hand in this controversial reshuffle. In recent weeks, another separatist minister, who cannot be named due to security reasons, is understood to have come under increasing pressure from senior officials in Moscow and the LNR leadership to toe the line.

A mid-level LNR ministry employee told VICE News: "Many top officials are now under pressure. It is a strange time of transition with many high-level power struggles. Tension and paranoia is rising — it is worse than six months ago. It all seems to be emanating from Plotnitsky and his inner circle."

There are not only internal tensions within the LNR but also external strains. According to the International Crisis Group, officials and leaders in the neighboring Donetsk People's Republic (DNR) "are privately critical of their LNR counterparts," accusing them of "corruption and … often failing to provide promised forces." The report describes the separatist leaders as "accidental rulers," guided "by mixed motives," who only achieved power via "the political and security vacuum created by the Yanukovych presidency's collapse."

Such divisions among Ukraine's separatist militants have not gone unnoticed by their masters in Moscow. According to recent reports, Vladimir Putin plans to send his envoy and close aide, Vladislav Surkov, to the LNR for high-level talks to resolve the rebels' leadership crisis and rein in their puppet leaders. There is even talk that Moscow is ready to give up Plotnitsky and his counterpart in Donetsk, Alexander Zakharchenko, in return for Kiev recognizing local elections.

Surkov, a shadowy figure and Kremlin ideologue, often characterized as the Rasputin of modern-day Russia, oversees Ukraine's rebel regions on Putin's behalf and is said to refer to Moscow's separatist proxies there as his "wards." According to an LNR insider, Surkov's secret visits to Luhansk in the past have been accompanied by city-wide cellphone blackouts, serving both as an extreme security precaution and a means of preventing leaks of confidential information.

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Public figures of the rebel insurgency are not the only ones to have fallen foul of an authoritarian regime which seized power amid the chaos of war. Ordinary civilians and military detainees, too, have suffered "gross and systemic violations of human rights" by armed members of the rebels' "repressive political regimes," according to a new report compiled by a coalition of local and international NGOs.

This report — entitled "Surviving Hell: Testimonies of Victims on Places of Illegal Detention in Donbas" — follows other dossiers that have detailed a catalogue of institutional torture: sleep deprivation, beatings, sexual violence, mock executions, amongst other horrors. Armed groups have subjected individuals to "inhumane conditions" and "cruel treatment" while holding them incommunicado in a legal vacuum that "creates impunity" for the culprits, investigators say.

'They broke my ribs, and my body was all black'

The accounts make for grim reading. One former prisoner described losing teeth and developing hemorrhages during savage beatings. Another claimed not to have been given anything to drink for four days and resorted to scooping up dirty water from the floor of his cell. And one victim was subjected to a torture technique dubbed "the elephant," in which his abusers attached a gas mask to his face and blocked the oxygen flow.

The account of one source — who is named in the report as "C-46" and was detained in Donetsk's former security headquarters — is particularly harrowing.

"They broke my ribs, and my body was all black. They beat me during and in between interrogations with hands, feet, and weapons. They tortured me with electricity. They handcuffed me to a metal bed, put wires on my hands and regulated the current. They touched my head and genitalia with a metal rod charged with electricity. They hit me with a ramrod. They hung me up to the ceiling, poured cold water in freezing temperatures…"

These, then, are the accounts of the nameless victims and survivors of the war in eastern Ukraine. For every prominent separatist commander taken out in a spectacular hit, dozens more civilians, volunteers and conscripted soldiers are subjected to a nightmarish regime of abuse and torture. For every Dryomov, there is a "C-46," whose physical wounds will heal far more readily than the psychological scars.

The conflict grinds on with little sign of resolution. Civilians caught in the crossfire are exhausted and violations continue to be committed with relative impunity. But the authors of the report are clear: all perpetrators must be held responsible.

"Detention in these illegal custodial facilities," they say, "is accompanied with assaults, mutilations, and torture of detainees on the scale that calls for the use of not only the domestic but also international justice mechanisms." Could Ukraine's rebels one day be tried as war criminals? In reality, as the country's blood feud grinds on, the prospect of anyone paying for their crimes seems remote. For now, minds are concentrated on which head might be next to roll.