Five days later the JNA, including Obrenović's battalion, launched a massive simultaneous assault, starting with the attack by the Serb Volunteer Guard paramilitary forces on Bijeljina. The attacks soon spread to Foča, Zvornik, Bosanski Šamac, Vlasenica, Prijedor, Brčko, and was punctuated by the blockading of the Bosnian capital of Sarajevo to the southwest.