In the decades prior to the turn of the twentieth century, the power vacuum resulted from the collapse of the USSR as well as territorial disputes of amongst various ethnicities, with plural ethnic-religious formations and lack of political development, caused the formation of South Caucasus region with an anarchic structure. This region with three independent republics of Azerbaijan, Armenia and Georgia was suffering from the lack of a common security regime and was influenced by regional and international actors. Meanwhile, opposing interests and goals of regional actors such as Russia, Iran, and Turkey as well as trans-regional ones such as the United States, NATO and the Zionist Regime, made the security environment of South Caucasus confronted with some new challenges caused by geopolitical rivalries. Meanwhile, contrary to its political and security challenges, South Caucasus stands in a high level due to its energy resources and geopolitical and geo-economic importance in international politics equations. Using library research methods and an explanatory – analytical method and with the aim of scrutinizing the impact of rivalry among regional and international actors in the South Caucasus, the present literature addresses the following question: What has been the impact of strategic approaches of regional and international actors on security issues in the South Caucasus? It seems that a negative competition among regional and trans-regional actors has increased in the South Caucasus and this has led to a continuous instability in this strategic sub-region.