The combatants of the war in Donbas included foreign and domestic forces.
As of February 2018, the number of southeastern army separatist forces was estimated at 31,000, of which 80% (25,000) were Donbas residents, 15% (≈5,000) were military contractors from Russia and other countries, and 3% (900–1,000) are regular Russian Armed Forces personnel. This ratio had changed significantly from previous years, with "the Russian command gradually filling the armies of the 'republics' with locals". since peaking in 2015.
Separatist insurgents
Donbas People's Militia Igor Girkin, a Russian citizen and FSB officer from Moscow who commanded the Donbas People's Militia in Sloviansk, initially denied Russian involvement in the insurgency. He said his unit was formed during the annexation of Crimea by the Russian Federation, and that two-thirds of its members were Ukrainian citizens. Girkin also said that the Sloviansk insurgents had agreed to work with the leadership of the Donetsk People's Republic, despite some conflict between insurgent groups. According to a spokesman for the Donetsk People's Republic, the militants that occupied Sloviansk were "an independent group...supporting the Donetsk protest", while insurgents in Sloviansk and Kramatorsk identified themselves as members of Pavel Gubarev's Donbas People's Militia. The group's forces at Sloviansk included some professional soldiers amongst their ranks, as well as retired veterans, civilians, and volunteers, while those in Donetsk have been confirmed to include former Berkut special police officers. When asked by The Sunday Telegraph where their weapons had come from, one veteran of the Soviet invasion of Afghanistan nodded at the Russian flag flying from the police station and said: "Look at that flag. You know which country that represents". An insurgent commander in Donetsk, Pavel Paramonov, told journalists he was from Tula Oblast in Russia. In Horlivka, police who defected were commanded by a retired Lieutenant Colonel of the Russian Army, later identified as Igor Bezler. Former Soviet military veteran Vyacheslav Ponomarev, who declared himself mayor of Sloviansk, said that he appealed to old military friends to take part in the militia: "When I called on my friends, practically all of whom are ex military, they came to our rescue, not only from Russia but also from Belarus, Kazakhstan and Moldova."
A former separatist militant corroborated these stories in an interview with Radio Free Europe. He said that fighters, including some Cossack units, arrived from Russia to support the separatists. Another interview with an insurgent from Saint Petersburg was published in Gazeta. He claimed to be fighting voluntarily as part of the Russian Imperial Movement.
In late July 2014, the local support for the militia within the city of Donetsk was estimated to be 70% by a local entrepreneur interviewed by Die Welt.Du wachst auf und plötzlich bist du im Krieg . Die Welt. 29 July 2014 Armed groups affiliated with the Luhansk People's Republic were merged with the Donbas People's Militia on 16 September to form the "United Armed Forces of Novorossiya".
Army of the South-East The Army of the South-East (, Armiya Yugo-Vostoka) was a pro-Russian militant group that occupied various buildings in Luhansk Oblast. According to The Guardian, their personnel include former members of the disbanded Berkut special police. They were affiliated with the Luhansk People's Republic, but were merged with the Donbas People's Militia on 16 September to form the United Armed Forces of Novorossiya.
Russian Orthodox Army
The Russian Orthodox Army (, Russkaya pravoslavnaya armiya), a pro-Russian insurgent group in Ukraine, originated in May 2014 as part of the insurgency. It reportedly had 100 members at the time of its founding, including locals and Russian volunteers. As fighting between separatists and the Ukrainian government worsened in Donbas, membership rose to 350, and later to 4,000. Notable engagements of the ROA include the June 2014 skirmishes in Mariupol and Amvrosiivka Raion. The headquarters of the ROA is located in an occupied Security Service of Ukraine (SBU) building in Donetsk city. Members swore allegiance to Igor Girkin ("Strelkov"), insurgent and Minister of Defence of the self-declared Donetsk People's Republic. According to the Defence Ministry of Ukraine, the ROA has been in conflict with another pro-Russian militia, the Vostok Battalion, which accused the ROA of looting, and of avoiding combat.
Vostok Battalion
The Vostok Battalion (, ; lit. "East Battalion") was formed in early May 2014. It is commanded by Alexander Khodakovsky, a defector from the Security Service of Ukraine. Khodakovsky is the chief of the DPR's security service, and of the Patriotic Forces of Donbas, an insurgent battalion.
Khodakovsky said that the "overwhelming majority" of his men came from eastern Ukraine. According to the US government funded Radio Free Europe/Radio Liberty, Vostok reportedly includes former members of the original Vostok Battalion, a special forces unit of the Russian intelligence directorate (GRU) that participated in the Second Chechen and Russo-Georgian Wars. The original battalion was incorporated in 2009 into a Russian Defence Ministry reserve unit that is based in Chechnya. Khodakovsky said he had about 1,000 men at his disposal, and that more "volunteers" with experience in the Russian security sector were expected to join the battalion. A report by Radio Free Europe said that there were suspicions that the battalion was either created directly by the GRU, or that it was at least sanctioned by it. The battalion includes both fighters from Russia and from Ukraine. A BBC News report said that the battalion was composed largely of untrained locals from eastern Ukraine, with a smattering of Russian volunteers. Colombian and United States citizens have volunteered in Vostok battalion. A number of the Vostok insurgents were killed at the First Battle of Donetsk Airport. 30 bodies were repatriated to Russia after the fighting. Some of the members said they received salaries of 100 US dollars a week, though they maintained that were only volunteers. An Armenian volunteer in the unit said the battalion was composed of Slavs, and that roughly 80% of militants were from Russia.
By late February 2015, 110 members of the battalion had been killed and 172 wounded in the conflict.
Police and military defectors and deserters In May 2014, the acting Ukrainian president Oleksandr Turchynov stated that numerous Ukrainian military and security personnel had joined the separatists, alongside stolen Ukrainian military equipment. In October 2014, Internal Affairs minister Arsen Avakov told journalists that about 15,000 Ukrainian policemen in Luhansk and Donetsk oblasts had defected to the separatists.15,000 police 'defected to Donbas separatists' . UNIAN. 16 October 2014.
Foreign groups
Cossacks Some identified maverick neo-Cossack volunteers,"Russians Find Few Barriers to Joining Ukraine Battle ". The New York Times. 9 June 2014. particularly Don Cossacks who live on both sides of the border,"Ukraine: Common history pulls in aid from west Russia ". BBC News. 23 June 2014."Historical Dictionary of Ukraine ". Ivan Katchanovski, Zenon E. Kohut, Bohdan Y. Nebesio, Myroslav Yurkevich (2013). p.135. are participants in the war, along with some self-styled neo-Cossack groups. Several of these Cossacks formed a paramilitary unit called the 'Terek Wolves Sotnia', a reference to a detachment of White emigre Cossacks that fought against the Soviet Union during the Second World War. Prominent fighters include Alexander "Boogeyman" Mozhaev (a Russian military veteran from Belorechensk) and the unit's commander, Evgeny Ponomarev. Ponomarev was killed in August 2014.
Although Cossack units have been prohibited from crossing the Russian border into Ukraine en masse, it has been reported that Russian elements tacitly support the individual fighters in crossing the border into Ukraine. The Cossacks claim that it is their faith in Cossack brotherhood, Russian imperialism, and the Russian Orthodox Church that has driven them to take part in the insurgency with the aim of conquering what they perceive as "historically Russian lands." Mozhaev also stated that some of the more extreme views of the Cossacks include destroying "the Jew-Masons," who they claim have been "fomenting disorder all over the world" and "causing us, the common Orthodox Christian folk, to suffer." On 25 May, the SBU arrested 13 Russian Cossacks in Novoaidar Raion.
Caucasian and Central Asian armed groups
The Foreign Affairs ministry of Ukraine said that the presence of foreign soldiers amounted to "undisguised aggression" from Russia, and "the export of Russian terrorism to our country". "There are grounds to affirm that Russian terrorists funnelled on to the territory of Ukraine are being organised and financed through the direct control of the Kremlin and Russian special forces," the ministry said. To date, reports and interviews have shown the presence of Chechen, Ossetian, Tajik, Afghan, Armenian, and various Russian paramilitary forces operating in Ukraine.
Chechen paramilitaries
Chechen paramilitaries were spotted in Sloviansk on 5 May 2014. Chechen president Ramzan Kadyrov threatened on 7 May that he would "send tens of thousands of Chechen volunteers to southern and eastern Ukraine if the junta in Kiev continued its punitive operations." It was reported that Kadyrov engaged in an aggressive recruitment campaign in Chechnya for this operation, and that there were recruitment centres for it in Grozny, Achkhoy-Martan, Znamenskoye, and Gudermes. The Kavkazcenter, the official website of the North Caucasus Islamic insurgency, reported that Chechen authorities had opened recruiting offices for volunteers wishing to fight in Ukraine, and that those offices had suddenly closed. Five lorries crossed the Ukraine-Russia border carrying militants aboard on 24 May, with some reports suggesting among the militants were veteran Chechen soldiers. On the following day, the Vostok Battalion arrived in Donetsk in a convoy of eight lorries, each filled with 20 soldiers. Several of the soldiers looked Chechen, spoke the Chechen language, and said that they were from Chechnya. Two insurgents told CNN reporters that these were Chechen volunteers.
Ramzan Kadyrov denied knowledge of the presence Chechen troops in Ukraine, but a separatist commander later confirmed that Chechens and militants of other ethnicities fought for the Donetsk People's Republic People's Militia. In the aftermath of the First Battle of Donetsk Airport, local authorities said that some wounded militants were Chechens from Grozny and Gudermes. One Donetsk resident said that the presence of Chechen fighters showed "that this war is not clean. It is artificially created. If this is an uprising by the Donetsk People's Republic, what are foreigners doing here?"
Chechen militants interviewed by the Financial Times and Vice News said that they became involved in the conflict on the orders of the Chechen president. President Kadyrov strongly denied these reports on 1 June. In his statement, he said that there were "74,000 Chechens who are willing to go to bring order to the territory of Ukraine", and that he would not send them to Donetsk, but to Kyiv. As of May 2015, majority of previously pro-Russian Chechen paramilitaries exited the conflict, because of the two known incidents with Zakharchenko and his people, according to Akhmed Zakayev.
Ossetian and Abkhaz paramilitaries