The war in Donbas, or the Donbas war, was a phase of the Russo-Ukrainian war in the eastern Donbas region of Ukraine. The war began in April 2014, when Russian paramilitaries seized several towns. Ukraine's military launched an operation against them, but failed to fully retake the territory. Covertly, Russia's military were directly involved, and the separatists were largely under Russian control. The war continued until it was subsumed by the full-scale Russian invasion of Ukraine in 2022.
In March 2014, following Ukraine's Revolution of Dignity, Russia occupied Crimea. Anti-revolution and pro-Russian protests began in Ukraine's Donetsk and Luhansk provinces, collectively 'the Donbas'. On 12 April, a commando unit led by Russian citizen Igor 'Strelkov' Girkin seized Sloviansk and other settlements in the Donbas. Separatists declared the Donetsk and Luhansk republics (DPR and LPR) as independent states. Russia covertly supported them with troops and weaponry. It only admitted sending "military specialists", but later acknowledged the separatists as Russian combat veterans. On 15 April, Ukraine began an "Anti-Terrorist Operation" (ATO). By August 2014, Ukraine had re-taken most of its territory. Russia responded by covertly sending troops, tanks and artillery into the Donbas, helping pro-Russian forces regain much of what they had lost. DPR leader Alexander Borodai said 50,000 Russian citizens had fought for the separatists by mid 2015, excluding the regular Russian troops that invaded.