Operation Vrbas '92 (Serbian: Операција Врбас '92) was a military offensive undertaken by the Army of Republika Srpska (Vojska Republike Srpske – VRS) in June–October 1992, during the Bosnian War. The goal of the operation was the destruction of a salient around the central Bosnian town of Jajce, which was held by the Croatian Defence Council (Hrvatsko vijeće obrane – HVO) and the Army of the Republic of Bosnia and Herzegovina (Armija Republike Bosne i Hercegovine – ARBiH). The intensity of fighting varied considerably and involved several major VRS offensive efforts interspersed by relative lulls in fighting. Jajce fell to the VRS on 29 October 1992, and the town's capture was followed by the destruction of all its mosques and Roman Catholic churches.

The fighting improved the safety of VRS lines of communication south of the Bosnian Serb capital of Banja Luka, and displaced between 30,000 and 40,000 people, in what foreign observers called "the largest and most wretched single exodus" of the Bosnian War. The ARBiH and HVO in Jajce were not only outnumbered and outgunned, but their units were also plagued by inadequate staff work, compounded by lack of coordination between separate command and control structures maintained by the two forces throughout the battle. The defence of Jajce also suffered from worsening Croat–Bosniak relations and skirmishes between the ARBiH and the HVO along the resupply route to Jajce. Ultimately, the outcome of the battle itself fueled greater Bosniak–Croat animosities, which eventually led to the Croat–Bosniak War. The VRS saw the cracking of the ARBiH–HVO alliance as a very significant outcome of the operation.

As the Yugoslav People's Army (Jugoslovenska narodna armija – JNA) withdrew from Croatia following the acceptance and start of implementation of the Vance plan, its 55,000 officers and soldiers born in Bosnia and Herzegovina were transferred to a new Bosnian Serb army, which was later renamed the Army of Republika Srpska (Vojska Republike Srpske – VRS). This reorganisation followed the declaration of the Serbian Republic of Bosnia and Herzegovina on 9 January 1992, ahead of the 29 February – 1 March 1992 referendum on the independence of Bosnia and Herzegovina. This declaration would later be cited by the Bosnian Serbs as a pretext for the Bosnian War. On 4 April, JNA artillery began shelling Sarajevo. At the same time, the JNA and the Bosnian Serb forces clashed with the HVO at the Kupres Plateau, capturing Kupres by 7 April.

The JNA and the VRS in Bosnia and Herzegovina faced the Army of the Republic of Bosnia and Herzegovina (Armija Republike Bosne i Hercegovine – ARBiH) and the Croatian Defence Council (Hrvatsko vijeće obrane – HVO), reporting to the Bosniak-dominated central government and the Bosnian Croat leadership respectively, as well as the Croatian Army (Hrvatska vojska – HV), which occasionally supported HVO operations. In late April, the VRS was able to deploy 200,000 troops, hundreds of tanks, armoured personnel carriers (APCs) and artillery pieces. The HVO and the Croatian Defence Forces (Hrvatske obrambene snage – HOS) could field approximately 25,000 soldiers and a handful of heavy weapons, while the ARBiH was largely unprepared with nearly 100,000 troops, small arms for less than a half of their number and virtually no heavy weapons. Arming of the various forces was hampered by a UN arms embargo introduced in September 1991. By mid-May 1992, when those JNA units which had not been transferred to the VRS withdrew from Bosnia and Herzegovina to the newly declared Federal Republic of Yugoslavia, the VRS controlled approximately 60 percent of Bosnia and Herzegovina.

Even though the Graz agreement, negotiated by Bosnian Serbs and Bosnian Croats aiming to partition Bosnia and Herzegovina in early May, proclaimed cessation of hostilities between the two groups, heavy fighting broke out between the HVO and the VRS in June, in eastern Herzegovina (Operation Jackal), and in the Sava River basin (Operation Corridor 92), in the north of Bosnia and Herzegovina.

While the fighting related to Operation Corridor 92 was still in progress, the VRS prepared to attack and destroy a salient around the town of Jajce in central part of Bosnia and Herzegovina, held jointly by the HVO and the ARBiH. The salient threatened Bosnian Serb lines of communication south of VRS-held Banja Luka and contained two hydroelectric power plants critical for electrical supply of Banja Luka region. The salient was held by between 3,400 and 5,500 HVO and ARBiH troops manning strong fortifications in difficult terrain. The VRS committed 7,000–8,000 troops of the 30th Infantry Division of the 1st Krajina Corps to the offensive codenamed Operation Vrbas '92. The 30th Division was under command of Colonel Stanislav Galić, until he was replaced by Colonel Dragan Marčetić in early September. The VRS troops included the 1st, 11th and 17th Light Infantry Brigades and 1st Mixed Antitank Artillery Battalion. Besides the numerical superiority, the VRS held a clear advantage in armour, deploying 20–30 tanks and adding 30–50 heavy artillery pieces to the force. Defence of Jajce was organised at municipal crisis headquarters level by mayor Midhat Karadžić, while the HVO force in Jajce was commanded by Stjepan Blažević.

The Jajce salient was supported via a 40-kilometre (25 mi) road running through a narrow corridor to the town of Travnik. In July, the VRS attempted to cut the supply corridor and isolate Jajce from Travnik before any effort was made to capture the salient, but the attacks failed to accomplish any significant headway. This prompted the VRS to switch to a gradual advance along three separate axes converging on Jajce directly instead. The move was designed to minimize VRS casualties and allow a systematic elimination of HVO and ARBiH defences around the town. ARBiH-HVO successfully defended Jajce from the VRS, in part thanks to the area's mountainous surroundings. In the same month, feuding between the Croatian Democratic Union (HDZ) and the Party of Democratic Action (SDA) over political control began and the HVO forcibly disbanded the Bosniak-led war presidency in Jajce in exchange for one that was pro-Croat.

The VRS launched the first major attack along the western approach to Jajce in mid-August. The attack pushed through the town's defences and the VRS arrived to within two kilometres (1.2 miles) of Jajce. After this breakthrough, the frontline stabilised for nearly a month before the VRS made another push towards Jajce. The advance came from the southwest of the town and the defenders were pushed back to within one kilometre (0.62 miles) from the town. In order to relieve Jajce, the ARBiH and the HVO launched a joint attack north of Bugojno and Novi Travnik against a flank of the VRS force attacking Jajce, but the offensive failed—gaining no ground at all and hardly making any impact on the VRS deployments around Jajce. The VRS continued shelling Jajce and started small-scale airstrikes in the area. That led the United Nations (UN) to declare the whole of Bosnia and Herzegovina a no-fly zone. A Central Intelligence Agency (CIA) analysis concluded that it is possible that the failure of the ARBiH–HVO counterattack prompted the HVO to agree on a short-lived truce with the VRS in early October. Besides a ceasefire, the agreement promised the Bosnian Serbs power supply from the hydroelectric power plants in Jajce salient if the Serbs stopped their offensive.