The issue on most people's minds these days is the legitimacy of force if Iran refuses to comply with the demand that its nuclear program be dismantled. In fact, the use of military force is enshrined in the United Nations Charter. Nevertheless, the use of force is only authorised if it falls under one of two categories: self-defence (Article 41 of the United Nations Charter), or Security Council authorization (Article 42 of the Charter, which was used to authorize the military response by the United States and its allies against Iraq to drive that country out of Kuwait in "Operation Desert Storm" of 1990-91).
According to the Charter, to deem self-defence lawful requires that an attack has already been launched against a victim state. If a state believes it must resort to a pre-emptive strike, it must give solid proof that the action is necessary and that the act of defence is proportional, according to principles outlined in the Charter. The threat must be proven to be clear and imminent, and only after peaceful alternatives have failed.
But much has changed since the UN Charter was written. Today, the existence of weapons of mass destruction (WMDs) strongly suggests that a preventative war may be the only reasonable course of action, with many legal experts now arguing that international laws must be updated to reflect the difficulty in proving capability and intent, and the ability of modern weapons to cause complete annihilation of an enemy. Of course, simple possession of WMD’s does not in itself imply intent to wage war.
However, Iran is already in violation of Article 2.4 of the UN Charter prohibiting threats of war:
"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..."In 1974, the General Assembly concluded that in situations where a state is implicated in terrorism, the very involvement is as if the State perpetrated the attack. In theory, a nation could invoke the right of self-defence against the neighbour state that provides tactical support for the terrorists. Article 3(g) of the UN's Definition of Agression, 14 Dec. 1974, prohibits "the sending by or on behalf of a State of armed bands, groups, irregulars or mercenaries, which carry out acts of armed force against another State..."
Iran actively supports anti-Israel terror through the funding of Hamas, Islamic Jihad and Hezbollah. And recall that in January 2002, Iran attempted to smuggle 50 tons of ammunition to Palestinians aboard the ship Karine A. In so doing, Iran also violated the 1997 International Convention for the Suppression of the Financing of Terrorism (the Financing Convention). Iran's nuclear program is clearly an extension of this animosity; proof continues to pour in that Iran is building nuclear weapons and not power plants as claimed.
If Israel chooses to strike first, she also has the support of precedent established by the United Nations itself. In 1967, the UN Security Council declined to condemn Israel's pre-emptive strike at the outset of the Six Day War, partly because Egypt’s troop build-up was clearly visible and their intent openly stated in public rhetoric.
In its defence, Iran's chemical weapons and ballistic missiles, and possibly its nuclear weapons program, may be meant to dissuade internal challengers and gain influence in the Persian Gulf and Caspian Sea regions. The development of these various weapon systems can also be seen as a reaction to Iran's own experience as a victim of attacks during the Iran-Iraq War. Iran also believes it is threatened by US influence in the Middle East and the Arab myth of Israeli expansionism
Nevertheless, based on its actions and words, Iran has repeatedly violated international law and the UN Charter, and must be dealt with appropriately. Israel is correct in its expectation that the UN must act to protect Member States from imminent attack. If the UN fails to do so, or is unwilling to do so, the rule of international law makes clear that in "a case of necessity, of self-defence, a State is authorized to enter and destroy or remove weapons and bases that may be used against it." [Oppenheim L., International Law, vol. 1 par. 130, pg. 266, 6th edition, London, 1944]