Russian people's militias in Ukraine in the context of "Luhansk People's Republic"

The Russia–Ukraine border is the de jure international boundary between Russia and Ukraine. Over land, the border spans five Russian oblasts and five Ukrainian oblasts. Due to the ongoing Russo-Ukrainian War, which began in early 2014, the de facto border between Russia and Ukraine is different from the legal border recognized by the United Nations. As of 2024, Russia is militarily occupying a significant portion of Ukraine, and Ukraine is militarily occupying a very small portion of Russia.

According to a 2016 statement by Viktor Nazarenko, the head of the State Border Guard Service of Ukraine, the Ukrainian government did not have control over 409.3 kilometres (254.3 mi) of the international border with Russia. This stretch of land was formerly controlled by pro-Russian separatists under the Donetsk People's Republic and the Luhansk People's Republic (see War in Donbas), both of which were annexed by Russia in September 2022, seven months after the beginning of the ongoing Russian invasion of Ukraine. Ukraine has also not had authority over the Kerch Strait since 2014, when Russia annexed Crimea; the Ukrainian administration was pushed out of Crimea and Russian checkpoints were set up at the boundary with Kherson Oblast.

The ongoing military occupation of Ukraine's Kherson Oblast (Russian: Херсонская область, romanized: Khersonskaya oblast) by Russian forces began on 24 February 2022, when Russian forces invaded Ukraine from Crimea. It was administrated under a Russian-controlled military-civilian administration until 30 September 2022, when the Russian government declared it had annexed the territory. Since then it administers it as an internationally unrecognized federal subject of Russia.

Russia captured the city of Kherson on 1 March 2022. Kherson was the only regional capital that Russia has managed to capture in the invasion, though the cities of Donetsk and Luhansk had been controlled by Russian-backed separatists since 2014. Most of the rest of Kherson Oblast fell to Russian forces in the early months of the invasion.

The Donetsk People's Republic (DPR; Russian: Донецкая Народная Республика (ДНР), romanised: Donetskaya Narodnaya Respublika (DNR), IPA: [dɐˈnʲetskəjə nɐˈrodnəjə rʲɪˈspublʲɪkə]) is a republic of Russia with a capital in Donetsk, established on an illegally annexed part of Donetsk Oblast, Eastern Ukraine.

The DPR was created by Russian-backed paramilitaries in 2014, and it initially operated as a breakaway state until it was illegally annexed by Russia in 2022.

The siege of Mariupol began on 24 February 2022 and lasted until 20 May, as part of the Russian invasion of Ukraine. It saw fighting between the Russian Armed Forces (alongside the Donetsk People's Republic People's Militia) and the Ukrainian Armed Forces for control over the city of Mariupol in southeastern Ukraine. Lasting for almost three months, the siege ended in a victory for Russia and the Donetsk People's Republic, as Ukraine lost control of the city amidst Russia's eastern Ukraine offensive and southern Ukraine offensive; all Ukrainian troops remaining in the city surrendered at the Azovstal Iron and Steel Works on 20 May 2022, after they were ordered to cease fighting.

Mariupol is located in Ukraine's Donetsk Oblast, and following the siege, it was initially controlled by the Donetsk People's Republic, supported by occupying Russian troops. However, it was later subjected to Russia's annexation of southeastern Ukraine, and remains under direct Russian control as of 2024.