As the world awaits Iran’s development of nuclear weapons, no legal doctrine allows any nation to use force against Iran, despite its support for terrorism and the professed goal of destroying Israel. The question for the international community is whether this prohibition of force against Iran has increased the risk of war. The UN Charter allows a nation to use force only if defending itself against an armed attack, regardless of the attack’s destructive potential. Yet the danger inherent in Iran’s possession of nuclear weapons, although their use is not imminent, probably exceeds the risks associated with an armed attack by a nation with only conventional weapons—which was the greatest threat when the international community adopted the Charter in 1945.

A new doctrine of nuclear preemption would authorize force based on the danger a nation presents rather than the imminence of attack. Such a doctrine would recognize that nations developing nuclear weapons with a record of committing crimes of aggression, crimes against humanity, genocide, or war crimes are more dangerous than nations that may soon attack. By clarifying circumstances beyond self-defense under which a nation can use force, this doctrine would be distinct from the murky concepts of preemption, prevention, and anticipatory self-defense in use today. It would provide a means to deter unstable leaders who intend to use nuclear weapons or transfer them to terrorists as soon as they possess them. The traditional doctrine of self-defense is incapable of deterring even the most objectively dangerous nation from developing nuclear weapons. The broadest interpretation of the UN Charter’s provision on self-defense (Article 51) allows the use of force only when an attack is imminent—a vaguely defined moment susceptible to self-serving interpretations.

The threat that Iran presents is becoming increasingly clear in the international arena. On April 9, 2007, President Mahmoud Ahmadinejad announced that “Iran has succeeded in development to attain production [of nuclear fuel] at an industrial level,” a reference to Iran’s development of centrifuges, which are used to manufacture highly enriched uranium and plutonium, the radioactive chemical element used as fuel for nuclear weapons. A party to the Treaty on the Non-Proliferation of Nuclear Weapons, in which it pledged not to develop nuclear weapons, Iran has violated its treaty obligations by concealing its nuclear program for 20 years. The rhetoric of Iran’s leaders has been no less worrisome, as President Ahmadinejad has seconded Ayatollah Khomeini’s statement that “Israel must be wiped off the map.”

Bound by the doctrine of self-defense, Israel has no legal justification under which to attack Iran’s nuclear production facilities prior to Iran’s imminent launch of a nuclear weapon. In an era of virtually unstoppable ballistic missiles, especially when Iran’s can travel from Tehran to Tel Aviv in under 10 minutes, self-defense essentially requires a target nation to sustain a nuclear missile attack before it can legally defend itself. In assessing the legality of the threat or use of nuclear weapons, the UN’s International Court of Justice issued an advisory opinion in 1996 that indicated a nation might be justified in using nuclear weapons pre-attack if it was necessary to save the nation. In other words, a nation facing a devastating nuclear attack would be justified in responding with a defensive nuclear attack of its own before the adversary’s first nuclear missile hit its target.

However, if Iran develops and transfers nuclear weapons, Israel has few practical options. If Iran transferred nuclear weapons or radiological material to terrorists, Israel would have no legal basis under the current international law on which to attack Iran. Israel could not justify using self-defense because it would not be facing an imminent attack by Iran. In fact, Iran’s transfer of weapons or material to terrorists might not even constitute an armed attack on Israel, which, according to the International Court of Justice, is a necessary precondition before any nation may attack another nation for its support of hostile proxy agents. Additionally, Israel would have no basis on which to conclude that its use of force against Iran would prevent terrorists from using nuclear weapons. Thus, according to current law, an Israeli attack on Iran would not only be unnecessary, it would be illegal. Israel’s resort to the UN Security Council would be futile because China and Russia, which supply Iran with weapons and technology, would veto any international action against Iran.

The international community should accept that Iran will probably use or transfer its nuclear weapons to terrorists. On April 17, 2007, General Peter Pace, Chairman of the US Joint Chiefs of Staff, reported that Iranian weapons intended for the Taliban had been seized for the first time in Afghanistan—after over five years of fighting. It has long been known that Iranian special forces, some of them captured inside Iraq, have assisted insurgents in operations against US soldiers in Iraq. In addition, Iran and Syria have supplied Hezbollah with 12,000 to 15,000 short-range rockets, which Hezbollah uses to strike at civilian centers in northern Israel. In August 2006, at the height of the Israel-Hezbollah conflict in Lebanon, the US blocked Iran from sending Chinese-manufactured cruise missiles to Hezbollah via Syria.

The only method to prevent a nuclear attack might be to prevent certain nations from developing nuclear weapons. The use of force against those nations could be based on the danger they pose rather than on the existence of an imminent attack. The concept of danger as a second legal justification for the use of force recognizes that the world community cannot bear the risk of the catastrophe that would ensue should terrorist nations or individuals acquire nuclear weapons. Evolving principles in international law might provide an additional justification for nations to use force against Iran or similar nations, although the justification would be very limited. Beginning with the International Military Tribunal in Nuremberg in 1945 and including the recent International Criminal Tribunals (Rwanda, Yugoslavia, and Sierra Leone) as well as the International Criminal Court, the world has condemned four grave crimes—aggression, crimes against humanity, genocide, and war crimes. Respective examples include planning or starting a war, widespread civilian killing, destroying religious or ethnic groups, and fighting outside the laws of war. Were Iran an individual before an international criminal court, it would probably be guilty of every grave crime.