In July 1995, troops commanded by Mladić, harried by NATO air strikes intended to force compliance with a UN ultimatum to remove heavy weapons from the Sarajevo area, overran and occupied the UN "safe areas" of Srebrenica and Žepa. At Srebrenica over 40,000 Bosniaks who had sought safety there were expelled. An estimated 8,300 were murdered, on Mladić's order.