By 1998, international pressure compelled Yugoslavia to sign a ceasefire and partially withdraw its security forces. Events were to be monitored by Organization for Security and Co-operation in Europe (OSCE) observers according to an agreement negotiated by Richard Holbrooke. The ceasefire did not hold and fighting resumed in December 1998, culminating in the Račak massacre, which attracted further international attention to the conflict. Within weeks, a multilateral international conference was convened and by March had prepared a draft agreement known as the Rambouillet Accords, calling for the restoration of Kosovo's autonomy and the deployment of NATO peacekeeping forces. The Yugoslav delegation found the terms unacceptable and refused to sign the draft. Between 24 March and 10 June 1999, NATO intervened by bombing Yugoslavia aimed to force Milošević to withdraw his forces from Kosovo, though NATO could not appeal to any particular motion of the Security Council of the United Nations to help legitimise its intervention. Combined with continued skirmishes between Albanian guerrillas and Yugoslav forces the conflict resulted in a further massive displacement of population in Kosovo.