First of all, I would like to thank you, CoolHandCox, for being willing to step in and provide cites where FinnAgain has stubbornly refused to do so. I’ve been looking forward to an international law debate on this topic, and we can now finally proceed!
Well, it looks like you’ve got both the general document I was expecting and the affirmative defense I was prepared to present.
What we know is that North Korea did, at some point, fire at Southern targets, which would, without more, contravene the Charter. But then we have the catch-all escape clause of Article 51:
“Nothing in the present Charter shall impair the inherent right of individual or collective 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. Measures taken by Members in the exercise of this right of self-defence 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.”
Note the vague wording. The only prerequisite for self-defense is that “an armed attack occurs against a [member state].” There is no requirement that said attack hit land, damage property, or cause casualties. There is no requirement that self-defense measures be immediate. There is no requirement that self-defense measures be proportionate. There is no mens rea requirement. No - you get attacked, you can fire back.
So that is clearly the defense North Korea would use here. Also note that North Korea would point out the following facts in support of its position:
(1) The two Koreas are in a perpetual state of war, rather than the state of peace that the Charter assumes. The Armistice did not end the war, which is technically ongoing. Thus, cross-borders attacks do not threaten peace; they merely perpetuate an ongoing war. Ongoing wars are generally governed by the Geneva Conventions rather than the UN Charter.
(2) The Charter charges the Security Council with applying and enforcing the document. As such, the Security Council must pass a resolution stating which party has breached the Charter, and in what way. No such resolution has been passed, so North Korea can not truly be said to have violated any aspect of the Charter, any more than a person can be said to be guilty of a crime without a judicial ruling to that effect.
(3) All parties to the conflict agree that escalatory self-defense is a valid and legal response to cross-border attacks. For example, both South Korea and the US recently stated that air-strikes can be used against North Korean targets in response to any North Korean “attacks.” Yonhap News Agency Notice that there is no talk of proportionality. North Korea has a strong argument that it should not be held to a higher standard than its enemies are willing to embrace.
Once again, note that Article 51 has no imminence requirement, nor does it require that one have a good faith fear for the safety of one’s populace. Thus, as long as South Korea attacked North Korean territory, the North can lawfully retaliate, even if it does not reasonably believe itself to be in danger.