International peacekeeping is one of the more interesting and one of the more important developments in contemporary world affairs. In June 1982 the United Nations Interim Force in Lebanon was brushed aside contemptuously by Israeli forces sweeping triumphantly to Beirut. The cost to the Israelis in casualties, domestic social cohesion and international opinion was too high for them to hand over the fruits of the invasion to a body deeply hostile to Israel. The United States in particular had confused and collapsed the distinctions between collective defence, collective security and international peacekeeping. While pacific settlement aims to facilitate the reestablishment and preservation of peaceful relations between disputants, peacekeeping is directed towards constructing firebreaks which stop an outbreak of hostilities either from consuming the belligerents totally or engulfing others. Similarly, community enforcement measures necessarily entail four elements that violate core principles of peacekeeping: defining aggression; determining that aggression has taken place; identifying the aggressor; military participation by the major powers.