After the Croatian Democratic Union won 1990 parliamentary elections in the Socialist Republic of Croatia, ethnic tensions between Croats and Serbs within the Republic worsened. The ethnic groups are also divided along religious lines as the Croats are Catholics while the Serbs are Orthodox Christians. The Yugoslav People's Army ("Jugoslovenska Narodna Armija" – JNA) confiscated the weapons of Croatia's Territorial Defence ("Teritorijalna obrana" - TO) forces to minimize resistance. On 17 August, tensions escalated into an open revolt by Croatian Serbs, centred on the predominantly Serb-populated areas of the Dalmatian hinterland around Knin, and parts of the Lika, Kordun, Banovina and eastern Croatia. This revolt was followed in January 1991, by two unsuccessful attempts by Serbia, supported by Montenegro and Serbia's provinces of Vojvodina and Kosovo, to obtain the Yugoslav Presidency's approval for a JNA operation to disarm Croatian security forces.