For almost two decades Sweden has been a part of NATO: s missions in Afghanistan to create security and ensure that the country will not become a safe haven for terrorist organisations. The discussion how to counter terrorism and insurgency in the 21st century is today a topic where the foundation of modern counterinsurgency is questioned. Critiques against counterinsurgency strategy states that counterinsurgency does not work but merely is a utopia. This essay has studied two periods of the ISAF mission in Afghanistan by testing Zambernardis theory of counterinsurgency trilemma, with the purpose to contribute with new information of conditions within counterinsurgency to the discussion. The theory aims to show that of the three main goals of all counterinsurgency’s; force protection, distinction between enemy combatants and non-combatants and the physical elimination of insurgents, only two can be achieved simultaneously. The study compared the two cases differences regarding casualties to reach the conclusions.The result of the study shows that ISAF achieved two goals simultaneously during the two periods in line with Zambernardis theory. The result of the study shows that when discussing counterinsurgency operations, the relationship between casualties in counterinsurgency’s ought to be included.