Anti-Terrorist Operation Zone, or ATO zone, was a term used by the media, public, the government of Ukraine, and the OSCE and other foreign institutions to identify Ukrainian territory of the Donetsk and Luhansk regions (oblasts) under the control of Russian military forces and pro-Russian separatists. As the 2014 pro-Russian unrest in Ukraine escalated with the arrival of armed militias, the Ukrainian government declared the start of an "Anti-Terrorist Operation" (ATO), marking the beginning of the War in Donbas. A significant part of ATO zone was considered temporarily occupied territory of Ukraine. In Minsk II protocols of 2015 it was referred to as 'certain areas of Donetsk and Luhansk regions'.