Russia's Duma has passed, and President Dmitry Medvedev has ratified, an agreement allowing the Russian military to maintain bases in Abkhazia and South Ossetia for 49 years, with automatic 15-year extensions after that.

The agreements refer to the 7th Military Base in Abkhazia, and the 4th in South Ossetia, which have evolved from the peacekeeping bases that Russia maintained before the 2008 war with Georgia. (For a details about the bases, a thorough, if slightly old, accounting was published in Russia in Global Affairs.) The bases host a total of about 7,000 troops, split evenly between the two breakaway territories.

A Russian analyst says in Izvestia that the agreements are mainly necessary for legal purposes:

Sergei Karaganov, chairman of the Russian Council for Foreign and Defense Policy, said the agreements’ ratification will make things a great deal easier for the Russian military.

“They are currently living in a legal grey zone, although they are not complaining because their bases are located in resort areas,” Karaganov said.

He said the agreements on these Russian bases will cement the secession of South Ossetia and Abkhazia from Georgia and make peaceful reunification impossible.

“Russia should be consistent in its actions. It has recognized these republics’ independence, now Russia must safeguard it,” Karaganov said.

It would seem that legality is a bit of a fig leaf when it comes to the Russian presence in the breakaway territories, especially in South Ossetia, which is dominated by Russia in so many extralegal ways. And the statuses of the two republics are unclear enough that to sign an agreement 49 years in advance seems like wishful thinking. Still, following on agreements of identical length with Armenia and Tajikistan, what I want to know is, why 49 years? I assume there's a reason all these deals are signed for that period, but I can't find what it would be. If anyone knows, drop me a line.

UPDATE: Reader William Cohen (not the former US defense secretary, but a recent IR grad from King's College, London) writes in with an intriguing theory on the 49 years:

In Judaism, there is a 'Jubilee Year' set aside every 50 years (detailed in Leviticus ch 25): this year is a special time for annulling debts, freeing slaves, and returning borrowed land. The idea is that no-one can buy/sell land permanently, only for a period of time up to 49 years after which it'd revert back to its original owner.

Theoretically it's a nice safety barrier to prevent hereditary poverty, or to prevent long-term violations of sovereignty... How the concept could've found its way into Russian foreign policy is another question!