The UN Charter prohibits a state from going to armed attack against another, with only a few exceptions: if the state can be considered to be forced to self-defense or if the Security Council has given its approval.
When Israel initiated massive bombings of Iran on Friday morning, it was said to be done in a preventive manner to meet a threat to the existence of the state of Israel: an Iran that is feared to be on its way to building nuclear weapons, but which has not yet done so.
Then the question is whether the danger of Iran attacking Israel is acute enough, says Jann Kleffner, who is a professor of international law at the Defense College in Stockholm.
And it probably is not. It depends, of course, on facts that we may not have before us now, but in broad terms, the right to self-defense is only available in the event of an ongoing armed attack or one that is imminent.
Stands outside the system
The threat that Iran's nuclear program could pose has not materialized sufficiently for it to constitute such an acute threat, Kleffner assesses. But the opportunities to test this legally - to hold Israel accountable for an act of aggression - are limited.
Neither Israel nor Iran attributes any jurisdiction to the UN's highest court, the International Court of Justice in The Hague (ICJ). And in a politically locked Security Council, the US is expected to continue to veto cases involving Israel. The General Assembly, however, has the opportunity to request an advisory opinion from the International Court of Justice.
It can be significant in the sense that you get the highest legal body within the UN to express itself in some way on the issue, but it is not legally binding, says Jann Kleffner.
Cautious reactions
What guidelines remain then? The international legal system is based on the will of states to act, emphasizes Professor Kleffner.
And if that will does not exist, or if there are certain very leading states that do not have an interest in international law being complied with, then you cannot do much more than international organizations and individual countries can try to invoke international law rules and take a stand on what is happening, he says.
There are some reactions, although quite cautious, which suggest that quite a few states do not believe that there is any legal basis for Israel's actions.
