Agreement on Friendship and Cooperation between Bosnia and Herzegovina and Croatia The Agreement on Friendship and Cooperation between Bosnia and Herzegovina and Croatia was signed by Alija Izetbegović , President of the Republic of Bosnia and Herzegovina , and Franjo Tuđman , President of the Republic of Croatia , in Zagreb on 21 July 1992 during the Bosnian and Croatian wars for independence from Yugoslavia . It established cooperation , albeit inharmonious , between the two and served as a basis for joint defense against Serb forces . It also placed the Croatian Defence Council ( HVO ) under the command of the Army of the Republic of Bosnia and Herzegovina ( ARBiH ) . Izetbegović , who had hoped to prevent Bosnia Herzegovina from falling under the influence of Croatia or Serbia , signed the agreement after Stjepan Kljuić , president of the Croatian Democratic Union ' s ( HDZ ) branch in Bosnia and Herzegovina , was replaced by Tuđman with Mate Boban , who blocked the delivery of supplies to Sarajevo where a siege was under way and had proclaimed an independent Croatian Republic of Herzeg - Bosnia ( HR - HB ) . The agreement fell apart in October after a number of events including the assassination of Blaž Kraljević , leader of Croatian Defence Forces ( HOS ) in Bosnia and Herzegovina , the fall of the areas of Posavina , Bosanski Brod , and Jajce into the hands of the Army of Republika Srpska ( VRS ) , and after a major battle broke out between the HVO and the ARBiH in Prozor . Preparation for war . In 1990 and 1991 , Serbs in Croatia and in Bosnia and Herzegovina had proclaimed a number of " Serbian Autonomous Regions " with the intent of later unifying them to create a Greater Serbia . Serbs used the well equipped Yugoslav People ' s Army ( JNA ) in defending these territories . As early as September or October 1990 , the JNA had begun arming Bosnian Serbs and organizing them into militias . By March 1991 , the JNA had distributed an estimated 51 , 900 firearms to Serb paramilitaries and 23 , 298 firearms to Serbian Democratic Party ( SDS ) . The Croatian government began arming Croats in the Herzegovina region in 1991 and in the start of 1992 , expecting that the Serbs would spread the war into Bosnia and Herzegovina . It also helped arm the Bosniak community . From July 1991 to January 1992 , the JNA and Serb paramilitaries used Bosnian territory to wage attacks on Croatia . On 25 March 1991 , Franjo Tuđman met with Serbian president Slobodan Milošević in Karađorđevo , reportedly to discuss partition of Bosnia and Herzegovina . In November , the autonomous Croatian Community of Herzeg - Bosnia ( HZ - HB ) was established , it claimed it had no secessionary goal and that it would serve a " legal basis for local self - administration " . It vowed to respect the Bosnian government under the condition that Bosnia and Herzegovina was independent of " the former and every kind of future Yugoslavia . " In December , Tuđman , in a conversation with Bosnian Croat leaders , said that " from the perspective of sovereignty , Bosnia - Herzegovina has no prospects " and recommended that Croatian policy " support for the sovereignty [ of Bosnia and Herzegovina ] until such time as it no longer suits Croatia . " In April 1992 , the siege of Sarajevo began , by which time the Bosnian Serb - formed Army of Republika Srpska ( VRS ) controlled 70 % of Bosnia and Herzegovina . On 8 April , Bosnian Croats were organized into the Croatian Defence Council ( HVO ) . A sizable number of Bosniaks also joined . The Croatian Defence Forces ( HOS ) , led by Blaž Kraljević in Bosnia and Herzegovina , which " supported Bosnian territorial integrity much more consistently and sincerely than the HVO " was also created . On 15 April 1992 , the multi - ethnic Army of the Republic of Bosnia and Herzegovina ( ARBiH ) was formed , with slightly over two - thirds of troops consisting of Bosniaks and almost one - third of Croats and Serbs . In the winter Bosniaks began leaving the HVO and joining the ARBiH which also began receiving supplies from Croatia . In May , HVO Major General Ante Roso declared that the only " legal military force " in HZ - HB was the HVO and that " all orders from the TO [ Territorial Defense ] command [ of Bosnia and Herzegovina ] are invalid , and are to be considered illegal on this territory " . Pressure and agreement . The Croatian government played a " double game " in Bosnia and Herzegovina and " a military solution required Bosnia as an ally , but a diplomatic solution required Bosnia as a victim " . Tuđman ' s Croatian Democratic Union ( HDZ ) party held important positions in the Bosnian government including the premiership and the ministry of defence , but despite this carried out a separate policy and refused for the HVO to be integrated into ARBiH . Jerko Doko , the Bosnian defence minister , gave the HVO priority in the acquisition of military weapons . In January 1992 , Tuđman had arranged for Stjepan Kljuić , president of the Croatian Democratic Union of Bosnia and Herzegovina ( HDZ BiH ) who favored cooperating with the Bosniaks towards a unified Bosnian state , to be ousted and replaced by Mate Boban , who favored Croatia to annex Croat - inhabited parts of Bosnia and Herzegovina . A rift existed in the party between Croats from ethnically mixed areas of central and northern Bosnia and those from Herzegovina . Izetbegović came under intense pressure from Tuđman to agree for Bosnia and Herzegovina to be in a confederation with Croatia ; however , Izetbegović wanted to prevent Bosnia and Herzegovina from coming under the influence of Croatia or Serbia . Because doing so would cripple reconciliation between Bosniaks and Serbs , make the return of Bosniak refugees to eastern Bosnia impossible and for other reasons , Izetbegović opposed . He received an ultimatum from Boban warning that if he did not proclaim a confederation with Tuđman that Croatian forces would not help defend Sarajevo from strongholds as close as 25 miles away . On 9 May , Boban , Josip Manolić , Tuđman ' s aide , and Radovan Karadžić , president of the self - proclaimed Republika Srpska , secretly met in Graz and formed an agreement on the division of Bosnia and Herzegovina , the Graz agreement . Beginning in June , discussions between Bosniaks and Croats over military cooperation and possible merger of their armies started to take place . The Croatian government recommended moving ARBiH headquarters out of Sarajevo and closer to Croatia and pushed for its reorganization in an effort to heavily add Croatian influence . In June and July , Boban increased pressure " by blocking delivery of arms that the Sarajevo government , working around a United Nations embargo on all shipments to the former Yugoslavia , has secretly bought . " On 3 July , Boban declared the independence of the Croatian Republic of Herzeg - Bosnia ( HR - HB ) . He was established as its president . It claimed power over its own police , army , currency , and education and extended its grasp to many districts where Bosniaks were the majority . It only allowed a Croat flag to be used , the only currency allowed was the Croatian kuna , its only official language was Croatian , and a Croat school curriculum was enacted . Mostar , a town where Bosniaks constituted a slight majority , was set as the capital . There was no mention on the defense of Bosnia and Herzegovina ' s territorial integrity . On 21 July , Izetbegović and Tuđman signed the " Agreement on Friendship and Cooperation between the Republic of Bosnia and Herzegovina and the Republic of Croatia " in Zagreb , Croatia . The agreement allowed them to " cooperate in opposing [ the Serb ] aggression " and coordinate military efforts . It placed the HVO under the command of the ARBiH . Cooperation was inharmonious , but enabled the transportation of weapons to ARBiH through Croatia in spite of the UN sanctioned arms embargo , reopening channels blocked by Boban . It established " economic , financial , cultural , educational , scientific and religious cooperation " between the signatories . It also stipulated that Bosnian Croats hold dual citizenship for both Bosnia and Herzegovina and for Croatia . This was criticized as Croatian attempts at " claiming broader political and territorial rights in the parts of Bosnia and Herzegovina where large numbers of Croats live " . After its signature Boban vowed to Izetbegović that HR - HB would remain an integral part of Bosnia and Herzegovina when the war ended . Aftermath . In the summer of 1992 , the HVO started to purge its Bosniak members . At the same time armed incidents started to occur among Croats in Bosnia and Herzegovina between the HVO and the HOS . The HOS was loyal to the Bosnian government and accepted subordination to the Staff of the ARBiH of which Kraljević was appointed a member . On 9 August , Kraljević and eight of his staff were assassinated by HVO soldiers under the command of Mladen Naletilić , who supported a split between Croat and Bosniaks , after Kraljević ' s HOS attacked the VRS near Trebinje . The HOS ' s advance into eastern Herzegovina and occupation of Trebinje angered Boban who had affirmed to Karadžić that Croat forces were uninterested in the region . The HOS was disbanded , leaving the HVO as the only Croat force . Bosnian officials suspected that Tuđman ' s government was involved . In late September , Izetbegović and Tuđman met again and attempted to create military coordination against the VRS , but to no avail . By October , the agreement had collapsed and afterwards Croatia diverted delivery of weaponry to Bosnia and Herzegovina by seizing a significant amount for itself . Boban had abandoned a Bosnian government alliance and ceased all hostilities with Karadžić . The dominant Croatian – Bosnian defense of Posavina fell apart after Tuđman and / or Gojko Šušak ordered the withdrawal of the Croatian Army , enabling the Serbs to gain control of the corridor and connect their captured territories in western and eastern Bosnia . On 8 October , the town of Bosanski Brod was abandoned by the HVO and left to the VRS . The pullout appeared to be a quid pro quo for the JNA withdrawal from Dubrovnik ' s hinterland that took place in July . On 9 October , the HVO signed a cease - fire with the VRS in Jajce in exchange for providing electricity . On 29 October , the VRS captured Jajce due to the inability of ARBiH and HVO forces to construct a cooperative defense . Shortly after the first major battle in the impending Croat – Bosniak war broke out after the HVO pushed ARBiH from Prozor and expelled the Bosniak population . About 300 Bosniaks were killed or wounded in the attack .