Dr. Okuk, when you have a failure of diplomacy you get war, in regard to war between the Sudan and South Sudan at the border, Article 51 of the United Nations Charter clearly recognizes “the inherent right of individual or collective self-defense if an armed attack occurs against a Member of the United Nations” by anyone.
Article 51 of the UN Charter “Nothing in the present Charter shall impair the inherent right of individual or collective self-defense 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. Measures taken by Members in the exercise of this right of self-defense shall be immediately reported to the Security Council and shall not in any way affect the authority and responsibility of the Security Council under the present Charter to take at any time such action as it deems necessary in order to maintain or restore international peace and security.”