President Bush asserts that America has the "sovereign authority to use force in assuring its own national security" and does not need a new vote of the United Nations Security Council. On the other hand, U.N. Secretary-General Kofi Annan has warned that "to go outside the Security Council and take unilateral action ... would not be in conformity with the [U.N.] Charter." Russian President Vladimir Putin and many others have agreed that such an attack would be illegal.

Which side has the better argument? And does it matter?

The answer to the second question is that it matters a great deal. Cynical leaders such as Putin and Jacques Chirac may not care about legal principles. But many people in their nations and around the world do care. The alarming, worldwide surge of anti-Americanism over the past few months owes much to the Bush administration's image as a dangerous bully that has scorned international norms and institutions. Fed by statements such as Ari Fleischer's February 28 suggestion that the president would insist on "regime change" even if Iraq voluntarily disarmed—which seemed to decouple Bush's determination to invade from any plausible self-defense rationale—this fear and hatred of the United States can hurt us in many ways. Its most direct harm is in degrading the international cooperation that is vital to winning the war against terrorism.

In fact, a very respectable legal case can be made that since Saddam has shown no intention of disarming, the United States is justified in using military force as a last resort. This case is stronger, as a matter of international law, than was the case for President Clinton's 1999 bombing of Kosovo and Serbia for 77 days, with neither U.N. Security Council authorization nor any plausible self-defense rationale. It is stronger than the case for President Clinton's 1994 plan to invade Haiti—the event turned out to be a bloodless occupation-without obtaining authorization even from Congress, let alone from the Security Council. And it is arguably stronger than the case for President Kennedy's threats and use of force during the 1962 Cuban missile crisis. Not to mention the numerous interventions by France in its former African colonies.

The legal arguments against invading Iraq rest mainly on the U.N. Charter. Article 2 bans "the threat or use of force against the territorial integrity or political independence of any state" without an affirmative Security Council vote, including the approval (or at least abstention) of all five permanent members. Article 51 recognizes only one exception: "the inherent right of individual or collective self-defense if an armed attack occurs." The last five words appear designed to outlaw the "pre-emptive" use of armed force until after an enemy has actually attacked.

The United States has two rebuttals. One is that the Security Council has authorized member states to disarm Iraq by force, both in 1991, in Resolution 687, which demanded destruction of all Iraq's chemical and biological weapons, and last fall, in Resolution 1441, which warned of "serious consequences" unless Iraq fully complied with its "disarmament obligations." But these interpretations seem legalistic at best, are disputed by most of the world, and are undermined by the abject failure of the U.S. and Britain to win a more explicit Security Council authorization.

The stronger argument is that in today's world—with rogue regimes busily developing weapons of mass destruction, with undeterrable terrorist groups bent on using them, and with trend lines pointing toward the probable massacres of hundreds of thousands of Americans unless something changes—the U.N. Charter cannot be and has not been construed literally. And the long-standing right, under international law, to use military force to prevent threatened or anticipated attacks must be construed broadly.

Bush critics stress that even apart from the U.N. Charter, this right of pre-emptive self-defense has been limited to using the minimum amount of military force necessary to stop an imminent attack, and has never justified a "preventive" act of war based on speculative fears that perceived enemies might attack at some future time.

True enough—as of 1945 or so. But "we no longer live in a world where only the actual firing of weapons represents a sufficient challenge toa nation's security to constitute maximum peril," as President Kennedy said in his October 22, 1962, speech announcing the naval "quarantine" of Cuba to force removal of the Soviet missiles. "Nuclear weapons are so destructive, and ballistic missiles are so swift, that any substantially increased possibility of their use or any sudden change in their deployment may well be regarded as a definite threat to peace." JFK's logic foreshadows that of the Bush administration's September 2002 "National Security Strategy of the United States," which stresses that the nation "must adapt the concept of imminent threat to the capabilities and objectives of today's adversaries," who have or seek weapons of mass destruction that—even more than missiles—"can be easily concealed, delivered covertly, and used without warning."

Sen. Edward M. Kennedy, D-Mass., and others have sought to distinguish today's situation from the Cuban missile crisis by saying that the threat was more grave and imminent then; that JFK won the approval of the Organization of American States (although not of the Security Council) for his "quarantine"; and that he rejected pressure from military advisers to bomb the missile sites.

None of these distinctions is persuasive. The threat of a missile attack from Cuba in or after 1962—which would have been suicidal for both the Cuban and the Soviet regimes—was, if anything, less imminent than the current threat of a biological or chemical attack on the U.S. by terrorist proxies secretly armed by Saddam. And even the danger of a Saddam-sponsored nuclear attack may well be greater, albeit less imminent, than the threat that JFK acted to avert in 1962.

While JFK's blockade of Cuba was both bloodless and far more prudent than a military attack would have been, it was clearly, under international law, an act of war—one that the OAS had no legal standing to authorize. And JFK threatened to launch a military attack. He apparently meant it, which is why Nikita Khrushchev backed down and withdrew the missiles. Saddam has proved impervious to threats. He has also persisted in pursuing weapons of mass destruction despite his defeat in the 1991 Gulf War, and despite Israel's 1981 bombing of Iraq's French-supplied nuclear plant, a preventive attack that has been vindicated by history.

Perhaps the most cogent critic of Bush's self-defense rationale, Thomas Graham, Jr., a career arms control lawyer who was President Clinton's special ambassador for nonproliferation and disarmament, has stressed that "it appears that Iraq has no air force, has virtually no ballistic missiles, is years away from a nuclear weapon, has a greatly weakened army," and has no means, other than terrorist agents, of delivering chemical or biological weapons. This, Graham argues, means that Iraq is not (unless attacked) "a short-term probable threat," especially as compared with North Korea and Al Qaeda.

All true. But chemical or biological weapons delivered by terrorist agents could kill a lot of Americans. In any event, the ultimate question is whether the unprecedented magnitude of the long-term threat that will loom over civilization itself if Iraq and other rogue regimes are allowed to develop nuclear weapons deliverable by terrorists justifies an unprecedented policy of using military force to prevent such proliferation whenever feasible. The answer, in my view, is yes. And I think that the great statesman Elihu Root, who in 1914 asserted "the right of every sovereign state to protect itself by preventing a condition of affairs in which it will be too late to protect itself," would agree.

None of this is to deny that attacking Iraq in the face of such broad international opposition carries grave risks, or that a more patient and diplomatic president might have won additional international support, or that the Bush administration had "developed a language and diplomatic style that seemed calculated to offend the world," in the words of Newsweek's Fareed Zakaria. The point here is that the Bush administration's problem is not lack of legal justification but perceived indifference both to the need for legal justification and to world opinion.

This image is badly in need of repair. A quick, successful invasion that looks more like a liberation than an attack on the Iraqi people would be a good start, especially if it validates the self-defense rationale by uncovering plenty of biological and chemical weapons and a nuclear program. And a humble vow by the victor to improve his flawed diplomacy, and to try much harder to show a decent respect for the opinions of mankind, might work wonders.

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