[1] Before his death, Šimić served as the President of the Organization of the League of Communists in the Yugoslav People's Army, thereby acting as head of the League of Communists of Yugoslavia (SKJ) in the Yugoslav People's Army (JNA).

On 31 January 1989, he issued an announcement in which he accused some politicians of "pushing the Yugoslav ship on the rocks".

[2] Šimić also added that "JNA will oppose, with all its might, anybody who wants to play dangerous games with achievements of our struggle and the socialist revolution".

[2] At one of the sessions where fierce discussions occurred, according to official version, he suffered a stroke and died.

[3] After the Yugoslav Wars had ended, Croatian journalist Franjo Deranja published a book, sourced mainly to Antun Tus, saying that it was probable that the Yugoslav People's Army leadership was at fault for Šimić's death.