US intervention 2021 - The legality issues of the US intervention in Afghanistan

Abstract
Before the establishment of UN, all nation-states were using immeasurable power at every opportunity that they have according to their interest. İt is because of that, there was no law to limit the use of force on that time. Therefore, the UN treaty is the only treaty which regulates the right of self-defense as well as use of force. İt is explicitly stated in article 51. Of UN treaty under which condition states can apply to the self-defense. According to UN treaty, the only exception of self-defense is armed attack. At the same time, according to unwritten law, it is necessity to supply the principle of ungenciy, necessity and proportionality. The right of self-defense is limited to protect of itself. İt is not immeasurable right. Recently, some states are trying to legitimize their aggressive acts throught “ preventive legitimate defense”. However, this situation has no validity in terms of İnternational law. The intervention of USA’S in 2001 was implemented based on the principle of “ preventive legitimate defense”. That is why, the walidity of this intervention is under discussion. The purpose of this intervention is to find unswer to the question of whether this intervention is valid in terms of İnternational law.