The authors of this paper analyze the relationship between the two regions from their unilateral declarations until the second half of 1992. The Serbian Autonomous Region of Krajina (later the Republic of Serbian Krajina) in Croatia and the Autonomous Region of Krajina (ARK) in the northwestern part of Bosnia and Herzegovina were the first, as formal-legal successors of municipal communities, to be unilaterally formed autonomous regions based on ethnic principles in the process of the dissolution of Yugoslavia. Both were proclaimed by unilateral decisions of the republican organizations of the Serbian Democratic Party (SDS) both in Croatia and in Bosnia and Herzegovina before Slovenia and Croatia declared independence. Immediately after these declarations, politicians from both Krajinas analyzed and publicly presented their views on the future status of the newly formed regions. One of the options was the unification of these two regions into one administrative unit or state, with the most prominent advocates being the leading politicians from both regions. In order to justify the formation of such an administrative unit, reports were published on the necessity of its formation as a separate entity within the “fragmented Yugoslavia” or Greater Serbian state. However, the question arose of how much such unification would diminish the influence of SDS political leaders from Bosnia and Herzegovina and who would actually be the new national leader among the Serbs west of the Drina River? This question, as it turned out, burdened the entire relationship between the political and military leadership in both the Republic of Srpska (RS) and the Republic of Serbian Krajina (RSK) in various phases of the dissolution of Yugoslavia. Despite disagreements and different positions on the unification of the two Krajinas and the question of their status, political and military cooperation was unquestionable in the first two years of aggression against the Republic of Croatia and the Republic of Bosnia and Herzegovina. Cooperation was particularly intense in the second half of 1992 when the 1st and 2nd Krajina Corps of the Army of the Serbian Republic of Bosnia and Herzegovina/Army of the Republic of Srpska, in cooperation with the police structures of the RSK and the Serbian Army of Krajina (SAK), were jointly tasked with implementing the Six Strategic Goals of the Serbian Republic of Bosnia and Herzegovina/Republic of Srpska. This cooperation was particularly evident in the “battle for establishing the corridor” between Krajina and Semberija as the Second Strategic Goal, or joint action in Operation “Corridor '92”. In this paper, we will analyze the period from the end of 1990 and the first half of 1991 when the unilateral declarations of the Serbian Autonomous Region of Krajina and the Community of Municipalities of Bosnian Krajina (ZOBK), later ARK, occurred, until September 1992 when the decision was made to cease the existence of autonomous regions in the RS. This is the period when mass atrocities were committed against Bosniak and Croatian civilian populations in the RSK and RS. In the second half of 1991, the Bosnian Krajina was a direct war zone from which units of the Yugoslav People's Army (JNA) carried out aggressive operations against Croatia, and in 1992, it became a symbol of crimes against civilians in Bosnia and Herzegovina. Areas under Serbian control became “ethnically cleansed”, and Bihać, as a city under continuous military action from the RS and RSK military forces, became one of the symbols of the siege. The question arises as to whether the strategic goals of the RS could have been realized if the two Krajinas had not closely cooperated? This is precisely one of the questions we will answer. In order to answer such and similar questions, an analysis of the role of military and police structures of both regions is necessary, both in crimes and in military operations in the Bihać region.