Since the fall of the Soviet Union, the two neighboring nations have generally enjoyed very close cordial relations. Iran and Russia are strategic allies and form an axis in the Caucasus alongside Armenia. Iran and Russia are also military allies in the conflicts in Syria and Iraq and partners in Afghanistan and post-Soviet Central Asia. Due to Western economic sanctions on Iran, Russia has become a key trading partner, especially in regard to the former's excess oil reserves. Militarily, Iran is the only country in Western Asia that has been invited to join the Collective Security Treaty Organization, Russia's own international treaty organization in response to NATO. While much of the Iranian military uses Iranian-manufactured weapons and domestic hardware, Iran still purchases some weapons systems from Russia. In turn, Iran has helped Russia with its drone technology and other military technology. Iran has its embassy in Moscow and consulates in the cities of Astrakhan and Kazan. Russia has its embassy in Tehran, and consulates in Rasht and Isfahan.