Unit for Special Operations (Serbian: Јединица за специјалне операције, romanized: Jedinica za specijalne operacije; abbr.

The unit's official commander Franko Simatović and its gray eminence Jovica Stanišić (head of RDB during the first half of Slobodan Milošević's rule) were convicted at International Criminal Tribunal for the former Yugoslavia for various war crimes.

[2] The origins of the JSO can be traced back to April 1991, on the eve of Croatian War of Independence, when a paramilitary group led by Franko Simatović and Dragan Vasiljković set off from Belgrade to Knin, capital of the self-proclaimed Republic of Serb Krajina.

According to several witness accounts, Radovan Stojičić "Badža", an official of the Serbian ministry of interior, was in charge of operations in Eastern Slavonia.

The goal was to assist the fledgling Autonomous Province of Western Bosnia, a Serb-allied Muslim entity fighting against the central Bosnian government.

The unit members provided protection for Jovica Stanišić, head of the Serbian State Security (RDB) who, acting as a mediator, arranged for the safe release of the hostages.

[10][12] In 1996, one year after the Dayton Agreement and the end of conflicts in Croatia and Bosnia, JATD was re-structured and renamed to Jedinica za specijalne operacije, or JSO.

In May-July 1998, the Mi-24V helicopters of the JSO took part in a joint effort to push KLA out of Kijevo, a strategic village on the Priština-Peć road.

On 3 October 1999, a vehicle column of Serbian Renewal Movement (SPO), one of Serbia's largest opposition parties at the time, was attacked while moving down Ibar Highway.

Members of the Special Operations Unit, JSO, Duško Maričić, Branko Berček, Nenad Bujošević, and Leonid Milivojević were sentenced to 14 years in prison.

[18] After a yearlong trial in Serbia's special court in Belgrade, a judge found Radomir Marković and Milorad Ulemek, guilty of planning and carrying out the assassination of Ivan Stambolić.

Later, in his book titled "Peti oktobar" ("October 5"), former State Security chief Radomir Marković claimed he was the one who ordered the unit to be deployed in Belgrade.

[21] The policy of the new government, especially regarding the indictment of the former Serbian war leaders by the International Criminal Tribunal for the former Yugoslavia, was met with explicit disagreement from the unit's commanding officers.

During this period, disillusioned Ulemek got involved in criminal activities of the so-called Zemun Clan, by providing both intelligence information and muscle for them.