Serbs controlled some suburbs of Sarajevo and the LINE OF CONFRONTATION ran near the middle of Sarajevo. The UN had its compound just on the Bosniak side. Further, UN soldiers have testified that the Muslim provoked and broke cease fires the most. A Ukrainian officer testified he heard OUTGOING mortars from just outside the compound where he and other UN staff were staying. He and the other soldiers believe it was the Muslims trying to get the UN hit by Serbs returning fire.
NOT
Is that why the tunnel was constructed UNDER Sarajevo Airport? It was used by Bosniak refugees and as a supply conduit into and out of the city over Mt Igman. The tunnel was made necessary by the deal made between the UN and the surrounding Serbian forces for continued UN usage of the airport.