Book excerpt: Russia has strengthened its military position in Central Asia and the South Caucasus through a combination of bilateral and multilateral initiatives. The Collective Security Treaty Organization (CSTO) has become the most important multilateral defense structure in the former Soviet Union and is an essential instrument in Russia's resurgence. The CSTO has expanded its missions, authorities, and capabilities. However, it faces both internal and external challenges, especially debilitating divisions among its members.