Recently, there have been unverified reports that Armenia received up to ten Su-27s from Russia in 2006. This may have been presaged by an Azeri source which reported in October 2005 that Armenia had bought "10 fighter jets", but that, according to Azeri military sources, only 2-3 of the aircraft were Su-27s; the remainder were purportedly Su-25 jets and Mi-24 attack helicopters. Ostensibly, these would have been procured on preferential terms under the provisions of the 2002 Collective Security Treaty Organization (CSTO) agreement. To date, however, there has been no confirmation of the receipt of any of these aircraft, and it is possible that any appearance of Su-27s in Armenia may have been a deployment of Russia's own aircraft to its airbase at Yerevan. (It has also been pointed out that the Soviets never based Su-27s in Transcaucasia because it was too difficult an environment for them to operate in. Armenia's small size limits operational maneuver room and makes it difficult for them to climb to sufficient altitude.)