Would a Military Strike Against Iran Be Legal?

Would a Military Strike Against Iran Be Legal?

By Peter Berkowitz - March 4, 2012

Despite increased diplomatic maneuvering by the United States and intensified international economic sanctions, the U.N. International Atomic Energy Agency’s most recent report concludes that the Islamic Republic of Iran is accelerating production of enriched uranium used in nuclear weapons, concealing the uranium it has enriched, and generally stonewalling IAEA investigations of its nuclear program.

Such conduct places Iran in flagrant violation of its obligations under international law. But it will fall to the elected leaders in Israel and the United States and not to the lawyers in those countries -- or for that matter at the United Nations -- to determine whether to launch a military strike on Iran’s nuclear facilities.

Nonetheless, the justice of such a strike is bound up with its lawfulness, and liberal democracies are dedicated to both. So in confronting the fateful decision -- both striking and not striking are fraught with peril -- U.S. and Israeli leaders (and the citizens to whom they are accountable) must decide whether, under international law, they would be acting within their rights, were they to conclude that diplomacy and economic sanctions had run their course, to use military force to destroy or substantially set back Iran’s nuclear weapons program.

Since the advent of the modern nation-state system 500 years ago, it has been recognized that states have a right and an obligation to protect their citizens from aggression.

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.

In immediate response to al-Qaeda’s Sept. 11 surprise attack, but also in view of the steadily increasing threat posed by the proliferation of weapons of mass destruction, the Bush administration’s 2002 “National Security Strategy of the United States” argued for a broader reading. It maintained that the use of preventive force would sometimes be necessary because of “the inability to deter a potential attacker, the immediacy of today’s threats, and the magnitude of potential harm that could be caused by our adversaries’ choice of weapons.” The failure of coalition forces to find weapons of mass destruction in Iraq after the American-led 2003 invasion does not affect the logic of the argument, even as it underscores the dependence of strategic judgments on sound intelligence.

In a September 2011 speech at Harvard Law School, John Brennan, the Obama administration’s top counterterrorism adviser, effectively embraced the Bush administration’s broader interpretation by calling for “a more flexible understanding of ‘imminence.’ ” To be sure, Brennan was discussing terrorist organizations. But the logic of his contention that the understanding of an “ ‘imminent’ attack should be broadened in light of the modern-day capabilities, techniques, and technological innovations” applies equally to rogue states.

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 Peter Berkowitz is a senior fellow at the Hoover Institution, Stanford University.  His writings are posted at and you can follow him on Twitter @BerkowitzPeter.

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