It is clear that efforts to combat terrorism depend on international cooperation, but international politics has complicated attempts even to define international terrorism. Discussions in international forums have inevitably bogged down in futile debate. Some see terrorism as an alternative mode of warfare used by nations or groups that lack the conventional means of waging war, not as something to be outlawed. Some, believing that the ends justify the means, seek to exclude from the definition anything done by those engaged in wars of liberation. Others have wanted to broaden the definition to include acts of violence and other repressive acts by colonial, racist, and alien regimes against peoples struggling for liberation.
The United States has tried to define terrorism objectively on the basis of the quality of the act, not the identity of the perpetrators or the nature of their political cause. The rationale is that all terrorist acts are crimes, and many would also be war crimes or "grave breaches" of the rules of war even if one accepted the terrorists' assertion that they wage war. Terrorist acts involve violence or the threat of violence, sometimes coupled with explicit demands and always directed against noncombatants. The perpetrators are usually members of an organized group whose purposes are political. And the hallmark of terrorism—actions that are carried out in a way that will achieve maximum publicity and cause major alarm—introduces a distinction between the victims of the violence and the target audience. Indeed, the identity of the victims may be secondary or even irrelevant to the terrorist cause. "Pure terrorism" is entirely indiscriminate violence.
The U.S. position never won universal endorsement, but ultimately, the international community has come to achieve a rough consensus on terrorism. Although the community of nations could not reach an agreement on a precise definition, it did denounce terrorism as a form of political expression or mode of armed conflict and managed to construct a corpus of conventions that identified and outlawed specific tactics: airline hijacking, the sabotage of commercial aircraft, attacks on airports, attacks on diplomats and diplomatic facilities, the taking of hostages, bomb attacks on civilian targets, and so on. This tactic-by-tactic approach gradually extended to cover virtually all the manifestations of international terrorism.