The advancing Bosnian-Serb army threatening to conquer the town of Srebrenica and other parts of Eastern Bosnia, as well as the number of atrocities carried out by Bosnian-Serb forces against civilian populations despite UN efforts led the Security council to establish six so-called UN Safe Areas throughout Bosnia in Sarajevo, Tuzla, Srebrenica, Bihać, Goražde and Žepa. One such Safe Area was established in Tuzla, a salt mining city 120 km from Sarajevo in the North-eastern region of Bosnia. Tuzla became a critical location due firstly to its status as a population centre in the country, with the population more than doubling in size from its pre-war population 170,000 inhabitants to over 370,000. Secondly, the strategic importance of the Tuzla Safe Area also stemmed from its proximity to the newly-established border between the Serbian controlled Republic of Srpska and the Bosniak controlled areas. Tuzla was also a strategic location in the war due to its possession of one of few large airfields in the country.