Debating the Legality of an Assault on Iran’s Nuclear Facilities

by Julian Ku

I expect the legal issues arising out of a possible attack on Iran’s nuclear facilities are going to get hotter in the coming weeks. Peter Berkowitz of the Hoover Institution offers this argument in favor of the legality of Israel’s attack drawing from the doctrine of “preemptive” self defense (h/t Jack Goldsmith at Lawfare).

The charter of the United Nations affirms member states’ obligation to refrain “from the threat or use of force against the territorial integrity or political independence of any state” and, while envisaging a vigorous role for the Security Council in managing the use of force, also affirms states’ “inherent” right of self-defense.

States need not absorb a blow before they resort to military action. When threats are imminent, customary international law recognizes a right of anticipatory self-defense, though of course its scope is disputed.

Authority can be found for both a narrower and broader reading of imminence. In the “Caroline affair” of 1842, U.S. Secretary of State Daniel Webster, advancing the most stringent interpretation of imminence to make the case against the destruction by the British in 1837 of an American steamer, argued that states which have claimed a right to strike first must be able to “show a necessity of self-defense, instant, overwhelming, leaving no choice of means, and no moment for deliberation.”

But as Yale historian John Lewis Gaddis shows in “Surprise, Security and the American Experience,” the United States has been claiming the right to use force against emerging threats since 1818, when John Quincy Adams, President James Monroe’s secretary of state, formulated the doctrine to justify Gen. Andrew Jackson’s raids into Spanish Florida. Long after Webster settled the Caroline affair amicably, Presidents Theodore Roosevelt, William Howard Taft, and Woodrow Wilson all argued that the United States had a right to use force against failed or rogue states whose conduct endangered international order, and all ordered American troops into action on that ground.

Bruce Ackerman of Yale has quite a different take of US views on preemptive self-defense over at the LA Times.

In 1981, the United States joined in the U.N. Security Council’s unanimous condemnation of Israel’s preemptive assault on an Iraqi nuclear reactor. British Prime Minister Margaret Thatcher put it bluntly: “Armed attack in such circumstances cannot be justified. It represents a grave breach of international law.”

In standing with the Security Council to condemn the Israeli raid, the Reagan administration was embracing a tradition of U.S. statesmanship that began with Secretary of State Daniel Webster. In 1837, the British were trying to suppress a revolt in eastern Canada. Because U.S. militias were assisting the uprising, the British launched a night raid into New York state, burning a U.S. ship, the SS Caroline, and sending it over Niagara Falls.

After lengthy negotiations, Webster gained British consent to a treaty that prohibited such preemptive strikes. The two sides agreed in 1842 that a cross-border strike was legitimate only if there was a “necessity of self-defense, instant, overwhelming, leaving no choice of means, and no moment for deliberation.” This Anglo-American formula remains a part of international law today.

The United States was also the central player at the decisive moment for self-defense in the 20th century: the judgment at Nuremberg. We remember these trials for their condemnation of genocide. But this was not their central focus. The main charge was that the Nazis had waged aggressive war — and this required the Allies to endorse the limited doctrine of self-defense enshrined in traditional law.

Even when the United States felt itself to be directly threatened during the 1962 Cuban missile crisis, President Kennedy did not invoke the right of preemptive self-defense. Although the risk of mass destruction was high, the president’s legal arguments were carefully constrained: When intercepting Soviet missiles on the high seas, Kennedy relied on the regional peacekeeping provisions of the U.N. Charter.

I’ll admit up front that I don’t find Ackerman’s precedents terribly powerful.  The Caroline principle sounds good, but there is little evidence that either the US or Britain adhered to it very consistently.  Nor does Nuremberg seem to me a very specific precedent against the factual issue here (Ackerman also fails to note that the recent ICC Review Conference at Kampala has hardly added much meat to his definition of preemptive self-defense or aggression). And Kennedy instituted what is essentially an act of war, a “blockade” of Cuba, even though he called it a “quarantine” to avoid invoking a war.

I don’t think Berkowitz’s argument is foolproof, either. But he does offer a more persuasive take to me.  In his view, Israel is uniquely threatened by a nuclear-armed Iran, whose leaders have made specific threats to use them against Israel.  Given the nature of such weapons, and the vulnerability of Israel to nuclear weapons, it is not hard to see a preemptive strike actually meeting the Caroline “instant, overwhelming, leaving no choice of means, and no moment for deliberation” standard.

All of this depends on the facts, of course.  Would a preemptive strike by Iran on Israel’s facilities also be legal, for instance? I think not, because Israel has not made credible threats (or any threats) to use those weapons, which it does not even acknowledge having.  But this is the kind of factual issue that needs parsing, and which is murky enough that we may get no satisfactory resolution of the legal question.

13 Responses

  1. Response…
    The inherent right of self-defense is expessly and unavoidably limited in Article 51 of the Charter by the phrase “if an armed attack occurs”!  The Caroline incident actually involved ongoing armed attacks on Canada by insurgents who had been supported in part by The Caroline.  See, e.g.  The Caroline incident does NOT support anticipatory self-defense, much less preemptive self-defense when an armed attack is not even imminent (if anticipatory self-defense could ever be lawful in view of the express limit in Article 51 of the Charter).  “imminent threat” (or “emerging threats”) is, of course, nonsense!  What that phrase means is that a threat has not even emerged but is, in someone’s eyes, imminent.  As my article (above) demonstratss, the U.S. has often claimed the right of self-defense once an attack has occured.

  2. By now there must be a customary rule of international law that U.S. and her allies are allowed to use military force and the rest of the states are not.

  3. Response…
    With respect to Cuba, nearly everyone knows that the U.S. intentionally avoided the word “blockade,” because it would be an act of war, and used the word interdict (interdiction).  Also, the U.S. did not rely on Art. 51 self-defense, but on an authorization from a regional organization (the O.A.S.) for “regional action” under Art. 52 of the U.N. Charter (as it did in the case of the NATO authorization re: Kosovo).  Only the Arab League might give what might be an appropriate authorization for “regional action,” but that does not seem likely — or might it be NATO (threats to Turkey?)?.  The only legal argument left would be an interpretation of Art. 2(4) that I generally prefer — that, as it states, only three types of use of armed force are proscribed, and the latter type would fit an argument concerning regional peace (long-term) and security (perhaps coupled with Israeli self-determination and human rights), but even then there is the problematic phrase to interpret: use of armed force “against the territorial integrity” of Iran.  Most states would consider that an armed attack on Iran’s missile and nuclear installations would be covered by that phrase. And Israel was condemned by the Security Council when it took out the Iraqi nuclear reactor.

  4. “Historically, there are abundant illustrations (up to and including World War I) of anticipatory use of inter-State force. Still, none of these cases is relevant to the period subsequent to the adoption of the United Nations Charter. The crux of the issue is that anticipatory use of force today, in response to sheer threats rather than an armed attack, would not be in compliance with the text of Article 51 of the Charter.”, Y. Dinstein. War, aggression and self-defence. Cambridge University Press, 2011. p.195.

  5. If you can’t distinguish between a preventive and a preemptive attack, you don’t have any business commenting on international law. Julian Ku is an embarrassment to Opinio Juris.

  6. “Given the nature of such weapons, and the vulnerability of Israel to nuclear weapons, it is not hard to see a preemptive strike actually meeting the Caroline “instant, overwhelming, leaving no choice of means, and no moment for deliberation” standard.”
    “Not hard to see?” (“even for Stevie Wonder”, you should add, to make the argument more legally convincing). I suppose so, if you are some right-wing editor posting propaganda and fear mongering material on the internet trying to sway the public opinion – which after the Iraqi debacle is pointing the other direction. What weapons? Iran has none. Even if it did have a nuclear weapon, I do not see how its possession would constitute “instant, overwhelming, leaving no choice of means, and no moment for deliberation” standard. Why aren’t India and Pakistan bombing each other by now? Cause they are more rational actors than Israel will ever be.

    Go back to the drawing board, a.k.a. the UN Charter.

  7. Since the UN charter does not prohibit the use of force unless it is used “against the territorial integrity or political independence of any state”, I suppose that you all invoke customary international law to deduce that a preventive strike against nuclear facilities is unlawful.
    Two questions:
    1. Why is the faithful adherence to the language of article 51, while at the same time ignoring the language of article 2 (4) of the charter?
    2. I understand that Margaret Thatcher’s statements are somehow “law”. Can we say the same about statements by George Bush or Netanyahu? Is there any valid mechanism to distinguish between one political statement and the other?
    May I also remind the experts that in the Nicaragua-US dispute the UK justice Sir Robert Jennings refrained from applying customary law and preferred the language of the charter.

  8. Just to comment on a detail (not connected to preventive and pre-emptive self-defence, which is indeed a crucial difference by the way): The IMT at Nuremberg did NOT condemn/judge genocide, as is claimed by Ackerman! The crime of genocide did not exist at that time (the Genocide Convention was adopted in 1948). The tribunal at Nuremberg had “only” jurisdiction over crimes against peace (what would be aggression now), war crimes and crimes against humanity (see Art 6 of the London Charter, available at The later had in addition to be connected to any of the two other crimes and in the end there were only two or so convictions for crimes against humanity only. And as a reminder: crimes against humanity is not the same as genocide! 

  9. “The correct interpretation of Article 2(4)…is that any use of inter-State force by Member States for whatever reason is banned, unless explicitly allowed by the Charter. It is noteworthy that, in the 1986 Nicaragua Judgment, the International Court of Justice pronounced that
    Article 2(4) articulates the ‘principle of the prohibition of the use of force’ in international relations. The principle was presented by the Court in a non-restrictive fashion, and a careful dissection of the Judgment will disclose that this is no accident. In the Armed Activities case of 2005, the Court put it even more succinctly: ‘[t]he prohibition against the use of force is a cornerstone of the United Nations Charter’.”, Dinstein, War, aggression and self-defence, p.90-91.

  10. —->whose leaders have made specific threats to use them against Israel<—

    Sorry, but that's a nonsense. The leaders of Iran have never steers they will attack Israel with nukes. You are inferring this from other remarks they have made, which means your whole argument is based on a lie.
    Furthermore the threats Iran has made, e.g that the 'Zionist regime will pass from the pages of time' are often cited, but for some reason western MSM doesn't cite Iran's leaders when they call for full democratic rights for all in historic Palestine – which would if it came to pass, nullify Israel as a majority Jewish (and thus Zionist) state. Also western MSM never cite Ahmadinejad's admission that if the Palestinians decided to allow Israel to remain a Zionist/Jewish stare, he would accept their decision.
    As regards Israel being legally entitled to attack Iran, sorry no dice. But when was Israel ever bound by legal requirements?

  11. Long screeds cannot reverse the language of the charter even if Dinstein wrote them. Dinstein also claims that Gaza is under Israeli occupation. So?

  12. @Yaniv
    The full article 2(4) provides 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, or in any other manner inconsistent with the Purposes of the United Nations.
    Thus the literal reading of the article is not that it is restricted to “territorial integrity or political independence”. But to all other use of force. The self-defence (article 51) and Chapter VII are only exceptions to the general ban on the use of force for any reason. And there is a logic in that. When the rules of use of force where put on paper, one wanted to prevent any possible abuse of the rules. This is because one knew from history that states always find cheap excuses to start wars. And this is the best rule of thumb: the rules of military force should be interpreted in such a manner as to avoid abuses.

  13. Let’s discuss the language first. The phrase: “or in any other manner inconsistent with the Purposes of the United Nations” refers to jus in bello rules. This is why the word manner (instead of purpose) is being used. At any rate, had the intention been to avoid any use of force why not simply stating so?
    As for the claim that when the charter was drafted, it meant to “prevent any possible abuse of the rules” (your words) this is simply wrong once again: the charter drafters had in mind the conduct of Nazi Germany and Japan. They never meant to outlaw any use of force. As a matter of fact, I think that you confuse between your own personal agenda and what the drafters had in mind. This radical agenda is unfortunately shared by many international law experts. The sad outcome is that besides some insignificant lip service nobody pays attention to what they are saying.

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