in Zagreb, representatives of the Government of Croatia and the local Serb authorities in UNPAs concluded a cease-fire agreement aiming to achieve a lasting cessation of hostilities. Concurrently, the mandate of UNPROFOR was extended for another six months, and reinforcements were sent, amounting to 10,000 troops, a few hundred policemen, and observers. During 1994, UNPROFOR troops in Bosnia came under increased military attacks, resulting in several clashes (Operation Bøllebank, Operation Amanda) with Bosnian Serb forces. Assault against safe areas Shortly after the cease-fire between Croat and Serb forces, the Bosnian Serbs launched an assault against the Safe area of Goražde, heavily shelling the town and surrounding villages. Protests and exhortations from the UN Security Council turned out to be ineffective, and on 10 and 11 April 1994, NATO launched airstrikes against Bosnian Serb positions. In retaliation, Bosnian Serb forces captured many UN personnel, using them as human shields at sites expected to be bombed. The bombings turned out to be much less effective than the recent Gulf War, which had conditioned the public's understanding of airstrikes. In spite of NATO's demonstration of air power, and protests of good faith from the Serbs, the shelling continued. In a similar situation to what had happened in Sarajevo, an ultimatum was issued, and by the 24 April, most of the Serb troops had complied. These incidents led to another reflection about the status of the Safe Areas. Attempts at peace Several Peace Plans had been rejected (the Carrington-Cutiliero plan, the Vance-Owen plan, the "HMS Invincible" package, the Owen-Stoltenburg plan, and the European Union Action Plan). At the end of July, a blueprint was designed by the Contact Group, which consisted of the United States, United Kingdom, France, Germany and Russia, and was subsequently accepted by the Croat, Serb and Bosnian parties. The Bosnian Serbs, however, refused to accept the plan. In early August, in an attempt to coerce the Bosnian Serbs into accepting the plan, the Serbian government cut political and economic relationships with the Bosnian Serb leaders - a decision welcomed by the UN Security Council. On 23 September, the UN Security Council officially welcomed the agreement of the warring parties to the peace plan, condemned the Bosnian Serb refusal, and strengthened the sanctions against the Bosnian Serb entity. Bosnian Serb Isolation On 23 September 1994, in retaliation to the Bosnian Serb obstruction to the Peace Plan, the UN Security Council, adopted