Although Armenia's trade with EU states far exceeds that with Eurasian Union members Russia, Belarus and Kazakhstan combined, Armenia is dependent on Russia for security. Armenia's alliance with Russia, and its membership in the Collective Security Treaty Organization, is seen by Armenia as a counterbalance to Azerbaijan’s sharp hike in military spending (Azerbaijan bought tanks, artillery cannons and rocket launchers worth billions of US dollars from Russia in 2011, 2012 and 2013)..</ref> This is seen by Armenia as a threat given that the first Nagorno-Karabakh War (an armed conflict that took place from 1991 to May 1994 between Armenia and Azerbaijan) remains unresolved. Russia (also) has a military presence in Armenia, the Russian 102nd Military Base is an active base located in the city of Gyumri.