Self-defence is one of the most important exceptions to the principle of prohibition of use of force. For many years, has been objected by the opinions that claim basic changes on the terms of exercise of this right. The global reaction as well as the United States to 11 September 2001 attacks confirms this claim. But the International Court of Justice has, clearly, considered the "occurrence of an armed attack by a state" as an essential term for the applying the right of self-defence, but this term dose not exists in terrorism attacks.
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