Article 2 of the Charter states that all members "shall refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any state." Trump's threat to totally destroy North Korea violates that mandate. In addition, the preemptive use of force violates the Charter.
The only exceptions to the Charter's prohibition of the use of force are self-defense or approval by the Security Council.
Self-defense, under Article 51 of the Charter, is a narrow exception to the Charter's prohibition of the use of force. Countries may engage in individual or collective self-defense only in the face of an armed attack. In order to act in lawful self-defense, there must exist "a necessity of self-defense, instant, overwhelming, leaving no choice of means, and no moment for deliberation," under the well-established Caroline Case.
North Korea has not attacked the United States or another UN member country, nor is such an attack imminent.
Moreover, the Security Council has not authorized any country to use military force against North Korea. The council resolutions that establish sanctions against North Korea end by stating the Council "decides to remain seized of the matter." That means that the Council, and only the Council, has the authority to approve military action.
Both Trump's threat to use military force against North Korea and the mounting of a preemptive strike would violate the Charter.
The Crime of Genocide
By stating the intention to totally destroy North Korea, Trump has threatened genocide.
The crime of "genocide," as defined in the Rome Statute for the International Criminal Court, is committed when, with the intent to destroy, in whole or in part, a national, ethnical, racial or religious group, any of the following acts are committed: killing members of the group, causing serious bodily or mental harm to members of the group, or deliberately inflicting on the group conditions of life calculated to bring about its destruction in whole or in part.
Trump's threat to totally destroy North Korea, if carried out, would destroy, in whole, the national group of North Koreans. That would amount to genocide.
Crimes Against Humanity
Under the Rome Statute, "crimes against humanity" include: the commission of murder as part of a widespread or systematic attack against any civilian population; or persecution against a group or collectivity based on its political, racial, national, ethnic or religious character, as part of a widespread or systematic attack against any civilian population.
Trump's threat to totally destroy North Korea, if realized, would constitute a widespread and systematic attack against the civilian population of North Korea, which would amount to a crime against humanity.
The War Crime of Collective Punishment
The crime of "collective punishment" is a grave breach of the Fourth Geneva Convention, which is considered a war crime. Collective punishment means punishing a civilian for an offense he or she has not personally committed.
If Trump were to make good on his threat to totally destroy North Korea, he would be punishing the civilian population for offenses committed by the North Korean government. This would constitute the war crime of collective punishment.
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