Russia–Ukraine border

From internal line to international border

In the Soviet Union the boundary between the Russian and Ukrainian republics was an internal, administrative line.^[3] Crimea was moved from the Russian republic to the Ukrainian one in 1954.^[4]

Ukraine declared independence in August 1991 and confirmed it in a referendum. In December it helped set up the Commonwealth of Independent States, whose founding agreements promised respect for each other’s territorial integrity and existing borders.^[3] There was no agreement, though, on how the old internal borders would be defined or marked on the ground; that was left to later talks.^[3]

In the Budapest Memorandum of December 1994, Russia, the United States and Britain committed to respect Ukraine’s post-Soviet borders, and Ukraine gave up the Soviet nuclear weapons on its soil. A friendship treaty in 1997 affirmed Crimea as Ukrainian.^[4]

The 2003 treaty

Presidents Vladimir Putin and Leonid Kuchma signed the Treaty on the Russian-Ukrainian State Border in Kyiv on 28 January 2003, and it came into force on 23 April 2004. It took as its basis the administrative boundary between the two Soviet republics when the USSR dissolved, and came with an agreed description and atlas of the line.^[1]

According to Chatham House, Russia had long argued that the border should stay open and that marking it on the ground was an unnecessary cost, and the treaty did not settle demarcation or the boundary in the Sea of Azov and the Kerch Strait.^[3] A separate 2003 agreement treated the Azov Sea as shared internal waters, leaving its division for later.^[3]

“The basis of the border is the administrative boundary between the RSFSR and the Ukrainian SSR at the time of the dissolution of the USSR”^[1]

2014 and 2022

In March 2014 Russia annexed Crimea after a referendum that Kyiv and most of the world rejected.^[5][4] In April armed pro-Russian groups seized government buildings in Donetsk, Luhansk and other eastern cities, while an estimated 40,000 Russian troops massed just across the border.^[5]

Russia built up forces along the border from late 2021. On 21 February 2022 Putin recognised the self-proclaimed republics of Donetsk and Luhansk, and ordered Russian troops into Ukraine as “peacekeepers”. The full invasion followed, including from Belarus and north out of Crimea.^[6]

After votes held from 23 to 27 September 2022 in parts of the Donetsk, Kherson, Luhansk and Zaporizhzhia regions, Russia declared them annexed. On 12 October 2022 the UN General Assembly said the votes and the “attempted illegal annexation” had no validity under international law, and reaffirmed Ukraine’s internationally recognised borders.^[2]