Dividing Bosnia was pre-agreed between the Croatian and Serbian presidents
Evidence
It is now well documented that at a meeting with Serbian President Slobodan Milosevic in the town of Karadjordjevo, Tudjman and Milosevic decided on a plan to partition Bosnia between Croatia and Serbia and to neutralize any political or social aspirations of Bosnia’s Muslim community.’ … The HVO was formed outside of the Bosnian army, on the pretext that it would fight to repel aggression by the Serb army. The underarmed Bosnians had no choice but to accept the arrangement. — Michael A. Sells, The Bridge Betrayed, 258