It is common for both parties in a conflict to describe each other as terrorists.On whether particular terrorist acts, such as killing non-combatants, can be justified as the lesser evil in a particular circumstance, philosophers have expressed different views: while, according to David Rodin, utilitarian philosophers can (in theory) conceive of cases in which the evil of terrorism is outweighed by the good that could not be achieved in a less morally costly way, in practice the "harmful effects of undermining the convention of non-combatant immunity is thought to outweigh the goods that may be achieved by particular acts of terrorism". Among the non-utilitarian philosophers, Michael Walzer argued that terrorism can be morally justified in only one specific case: when "a nation or community faces the extreme threat of complete destruction and the only way it can preserve itself is by intentionally targeting non-combatants,then it is morally entitled to do so".In his book Inside Terrorism Bruce Hoffman offered an explanation of why the term terrorism becomes distorted:

On one point, at least, everyone agrees: terrorism is a pejorative term. It is a word with intrinsically negative connotations that is generally applied to ones enemies and opponents, or to those with whom one disagrees and would otherwise prefer to ignore. What is called terrorism, Brian Jenkins has written, thus seems to depend on ones point of view.
This ideology will also allow the terrorists to place the blame on the victim, who is viewed as being responsible for the violence in the first place.The context in which terrorist tactics are used is often a large-scale, unresolved political conflict. The type of conflict varies widely; historical examples include:

Secession of a territory to form a new sovereign state or become part of a different state
Dominance of territory or resources by various ethnic groups
Imposition of a particular form of government
Economic deprivation of a population
Opposition to a domestic government or occupying army
Religious fanaticism

Responses
Responses to terrorism are broad in scope. They can include re-alignments of the political spectrum and reassessments of fundamental values. Specific types of responses include:

Targeted laws, criminal procedures, deportations, and enhanced police powers
Target hardening, such as locking doors or adding traffic barriers
Preemptive or reactive military action
Increased intelligence and surveillance activities
Preemptive humanitarian activities
More permissive interrogation and detention policiesThe term "counter-terrorism" has a narrower connotation, implying that it is directed at terrorist actors. Terrorism research
Terrorism research, also called terrorism studies, or terrorism and counter-terrorism research, is an interdisciplinary academic field which seeks to understand the causes of terrorism, how to prevent it as well as its impact in the broadest sense. Terrorism research can be carried out in both military and civilian contexts, for example by research centres such as the British Centre for the Study of Terrorism and Political Violence, the Norwegian Centre for Violence and Traumatic Stress Studies, and the International Centre for Counter-Terrorism (ICCT).