Some have doubted whether Article 51 of the Charter, which reaffirms the inherent right of self-defence if an armed attack occurs against a Member of the United Nations, until the Security Council has taken measures necessary to maintain international peace and security, is still sufficient in an age when an armed attack may come without warning, from a clandestine terrorist group, perhaps armed with weapons of mass destruction.
They have argued that force must sometimes be used preventively, and that they must be free to decide when their national security requires it.
Others have replied that that doctrine is in itself a grave threat to international peace and security since it might imply that any state has the right to use force whenever it sees fit, without regard to other states' concerns. And that is precisely the state of affairs which the United Nations was created to save humanity from.
Indeed, the first purpose of the United Nations, laid down in Article 1 of the Charter, is to take effective collective measures for the prevention and removal of threats to the peace.
We must show that the United Nations is capable of fulfilling that purpose, so that States do not feel obliged or entitled to take the law into their own hands.