The Nakhchivan Autonomous Republic, the world’s largest landlocked exclave, shares a 71 kilometer long de facto land boundary with Armenia to the east and north. Nakhchivan, historically part of Armenia, became an established district of neighboring Azerbaijan during Soviet rule and has remained a discontiguous part of Azerbaijan since the dissolution of the Soviet Union. Despite many other territorial disputes with Azerbaijan, Armenia does not claim Nakhchivan, which remains an undisputed part of Azerbaijan.

The de facto boundary stems from internal administrative lines established while both Armenia and Azerbaijan were under Russian control in the 19th and 20th centuries, both as part of the Tsarist Empire and later the Union of Soviet Socialist Republics (USSR). While Armenia and Azerbaijan have fought multiple wars tied to territory since independence from the USSR in the early 1990s, the southern boundary between Nakhchivan and Armenia has remained less contentious. 

Tensions have increased recently between Nakhchivan and Armenia. In July 2022, Armenian and Azerbaijani forces exchanged fire along the northern section of the Nakhchivan border. This comes amid the ongoing conflict between Armenia and Azerbaijan over control of the Republic of Artsakh/Nagorno-Karabakh. 

Armenia and Azerbaijan also share a primary boundary, which is de facto and largely undefined.