 The Croatian government responded to the blockade of roads by sending special police teams in helicopters to the scene, but they were intercepted by SFR Yugoslav Air Force fighter jets and forced to turn back to Zagreb.The Croatian constitution was passed in December 1990 categorizing Serbs as a minority group along with other ethnic groups.Babić's administration announced the creation of a Serbian Autonomous Oblast of Krajina (or "SAO Krajina") on 21 December 1990.