Russia–Ukraine border
The Russia–Ukraine border is the 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 border between Russia and Ukraine is different from the legal border recognized by the United Nations., 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 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, 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.
In 2014, as the Ukrainian government lost Crimea and a portion of the Donbas to Russia and Russian-backed separatists, respectively, it unveiled a plan called "Project Wall" through which it sought to erect a fortified border barrier along the rest of the international border, with the goal of blocking any further Russian incursions into the country. It was estimated that the barrier would cost around and take four years to complete. Construction began in 2015, but was suspended due to Russia's full-scale invasion of Ukraine in 2022.
On 1 January 2018, Ukraine introduced biometric controls for Russian citizens entering the country. On 22 March 2018, former Ukrainian president Petro Poroshenko signed a decree into law that required all Russian visitors to inform Ukrainian authorities of their reason for travelling to Ukraine before their date of entry. On 7 November 2018, the Criminal Code of Ukraine was amended to make illegal border crossings by Russians into Ukraine punishable by imprisonment for up to three years.
Since 30 November 2018, Ukraine has banned all Russian males aged 16–60 from entering the country, albeit with room for exceptions on humanitarian grounds., Ukrinform
There is only one checkpoint on the Russia-Ukraine border that is open to Ukrainians, Kolotylivka-Pokrovka, located between the Sumy Oblast in Ukraine and the Belgorod Oblast in Russia. Since 1 March 2020, Ukrainian citizens are required to use their "international passport" when crossing the Ukrainian border to enter Russia.
File:RIAN archive 305861 Hoptivka car border crossing.jpg|thumb|right|Ukrainian customs service officer checking a car at the land crossing between Ukraine's Hoptivka and Russia's Nekhoteyevka in April 2008.
History before 1991
Under the Russian Empire and the Soviet Union
The border has inherited its location from the administrative-territorial division between the Ukrainian SSR and the Russian SFSR. The first real demarcation took place in May 1918 in Kursk. After the fall of the Russian Empire, several factions sought to create an independent Ukrainian state, alternately cooperating and struggling against each other. Most of Ukraine was overrun by the Red Guards of Soviet Russia. With the help of the Central Powers, Ukraine managed to recover all its territories of "Ukrainian governorates" and also annexed a number of neighboring counties of Kursk and Voronezh governorates where the ethnic composition of the population was predominantly Ukrainophone. On 6 May 1918, a ceasefire agreement was signed in Konotop between Ukraine and Soviet Russia. Between the fighting sides a neutral territory between 10 and 40 km wide was established to prevent further aggression, but the Russian side decided to create guerrilla forces which were transformed into two "Ukrainian divisions".Peace talks started on 23 May 1918 in Kyiv, where the Russian delegation was headed by Christian Rakovsky and Dmitry Manuilsky, while the Ukrainian - by . On June 12, 1918, the sides signed a preliminary peace treaty. Further negotiations stalled due to a lack of consensus on the issue of the borders. The Ukrainian side was proposing an ethnic principle based on the already established political, geographical, and economic aspects, while the Russian side insisted on conducting a plebiscite in each populated place. On 22 June 1918, both sides finally agreed to go along with the Ukrainian proposition, while any contested issues would be decided by plebiscite. Yet any further negotiations led nowhere and were terminated by the Ukrainian delegation in October 1918 as it was becoming apparent that the Russian was using their time more for the pro-Soviet propaganda.
Border with the anti-Bolshevik Don Republic
More productive were negotiations between the Don Republic and Ukraine that started soon after the Don Republic formed its government on 16 May 1918. The Don side was presented by the Minister of trade Vladimir Lebedev and the Ambassador of Don to Ukraine General Aleksandr Cheriachukin, while the Ukrainian side - by the Minister of Foreign Affairs Dmytro Doroshenko.On 8 August 1918, the sides signed the treaty "About Basic Principles of Bilateral Relations", wherein each side agreed to renounce its territorial contests against the other, and borders were established based on the gubernatorial division of the Russian Empire. The Don-Ukraine border outlined the Oblast of Don Host to the west of the Don Republic and Yekaterinoslav, Kharkiv, Voronezh guberniyas to the east of Ukraine. To Ukraine also was ceded some territory of the right bank of the Kalmius river just east of Mariupol "to ensure the proper administration of the city and port". On September 18, 1918, between Don and Ukraine the Don-Ukrainian Commission was created for the administration of the Taganrog Industrial District, based in Kharkiv.
Second invasion by the Russian SFSR
After the second invasion of the Soviet troops during the Russian Civil War in 1919, the new Soviet government of Ukraine intended to retain all territorial gains of the Ukrainian national government. However, after several rounds of negotiations, the border between the "Ukrainian governorates" and the "Russian governorates" was left intact. It also was agreed that Ukraine would border Crimea at the Perekop Isthmus. On March 10, 1919, a border treaty was signed between the Russian SFSR and the Ukrainian SSR.On April 24, 1919, the Ukrainian SSR was stripped of four counties of the Chernihiv Governorate that on the unilateral decision of the People's Commissariat of Foreign Affairs of the Russian SFSR were transferred to the newly created Gomel Governorate. On April 28, 1919, the Central Committee of the Communist Party of Ukraine simply acknowledged it.
File:Soviet Union Administrative Divisions 1989.jpg|thumb|250px|Map of the Soviet Union between 1954 and 1991, including the Ukrainian SSR and the Russian SFSR.
After the USSR was formally created in 1922 and due to the onset of the administrative division reform, issues emerged. The Ukrainian government claimed mainly some parts of the Kursk and Voronezh gubernia, which were home to a Ukrainian-speaking population. As a result of the border dispute of the 1920s, Ukraine was granted approximately one-third of the claimed territories, while the Taganrog and Shakhty districts went back to the RSFSR. By 1927, the administrative border between the RSFSR and Ukrainian SSR was established.
1954 transfer of Crimea to Ukraine
In 1954, First Secretary of the Communist Party of the Soviet Union Nikita Khrushchev transferred the peninsula of Crimea from the Russian SFSR to the Ukrainian SSR. This event was viewed as an insignificant "symbolic gesture", as both republics were a part of the Soviet Union and answerable to the government in Moscow. Crimean autonomy was re-established after a referendum in 1991, 11 months prior to the dissolution of the Soviet Union.History since 1991
In 1991, Ukraine as a new independent state inherited the territory and the boundaries of the former Ukrainian SSR. At the time the Russia–Ukraine border was an administrative line, which was not delimited nor demarcated. Ukraine has been trying to establish a proper border since.On December 8, 1991, the Russian SFSR, signed the Belovezha Accords with Ukraine, including the Agreement Establishing the Commonwealth of Independent States wherein the parties agreed to "recognise and respect one another’s territorial integrity and the inviolability of existing borders". A similar pledge was made in the Alma-Ata Protocol signed by eleven states on December 21, 1991. These treaties were both quickly ratified by Russia and Ukraine in December 1991.