Russia will build an inter-service military base in the breakaway Georgian republic of Abkhazia that will strengthen position in the Caucasus and the Black Sea.
An agreement on a combined land, air and naval base was signed on the sidelines of Abkhaz President Sergei Bagabsh's visit.
The base is designed “to protect Abkhazia's sovereignty and security, including against international terrorist groups”, said the document.
The agreement is valid for the next 49 years, after which it may be automatically prolonged every 15 years.
Russia and Abkhazia also signed a host of bilateral agreements on cooperation in the defence and economic fields.
“These agreements provide a foundation for the peaceful development of Abkhazia as an independent state,” said Russian President Dmitry Medvedev .
Russia recognised Abkhazia and South Ossetia, another separatist region of Georgia, in August 2008 after its military crushed Georgian forces attempting to retake South Ossetia. Moscow signed defence treaties with both territories.
The military base in Abkhazia, which will accommodate up to 3,700 troops, will project Russia's air and naval power across the Caucasus and the Black Sea and will counterbalance the ongoing build-up of U.S. military presence in the coastal states of Romania and Bulgaria. Russia also has a military base in the former Soviet republic of Armenia.