Nations define their relationships based on a number of interactions, but when it comes to going to war there should be only one standard: whether a nation’s very existence or a vital national interest at stake. Nothing else justifies the unintended consequences that inevitably result from warfare, and nothing less merits sending one’s sons and daughters to their possible deaths. In this age of nation-building and regime-change, that fundamental principle has been blurred, but it remains as true now as it did when Machiavelli first examined war’s place in the art of statecraft. War opens the gates of hell, releasing a Pandora’s box of evils. It should be the last option, only resorted to when all else fails.

The past eight years have seen several wars that have been unnecessary if judged by the national interest standard. Iraq posed no threat to the United States or to any of its neighbors. Afghanistan, one of the world’s poorest and most backward countries, was a threat to its neighbors and to the world only because it gave shelter to an international terrorist group. That al-Qaeda should have been attacked and removed from Afghan soil would be considered a proportionate and appropriate use of force by most observers, but nobody could have foreseen a completely bungled military operation that actually let the perpetrators of 9/11 go free and move to neighboring Pakistan. There followed a seven-year occupation of Afghanistan in support of an unpopular and corrupt puppet government that has culminated in an imploding security environment that has also spilled over into Pakistan.

The United States has apparently not learned from its mistakes as new President Barack Obama seems dedicated to continuing the occupation of Iraq while waging an expanding war in Af-Pak, as it is now being called. As if that were not enough, Obama is also being drawn somewhat reluctantly into a hot war with Iran, something that neoconservatives and Blue Dog Democrats alike seem to favor. Iran would seem to be an unlikely enemy, with virtually no industrial base and an economy less than 5 percent the size of the U.S. economy. Its military spending amounts to only about 1 percent of the U.S. defense budget. Nevertheless, Obama has repeated the Bush administration mantra that "all options are on the table" regarding Iran. He has stressed his willingness to talk with Tehran, but he has unwisely allowed himself to be locked into a timetable by visiting Israeli Prime Minister Bibi Netanyahu. If the negotiations route does not show solid results by the end of the year, Washington will be committed to moving toward a punishing sanctions regime. Netanyahu wants the U.S. to do his fighting for him against Iran, and he wants to shift the narrative away from his avoidance of negotiations with the Palestinians, so a focus on a short timetable centered on Iran suits him very well.

Obama is clearly uneasy with the prospect of war with Iran. Admittedly, sanctions are not war, but they create an environment where armed conflict is just one small step away. If a resolution moving through Congress is any indication, sanctions could include blocking the import of refined petroleum products. As Iran, a major petroleum exporter, has only limited refining capacity, the country’s economy would grind to a halt, resulting in catastrophic hardship for most of the Iranian people. Many would consider the sanctioning of Iranian energy imports to be an act of war. It would also reopen old wounds and pit the United States against most Europeans, who are rightly wary of yet another war in the Middle East.

Israel and its supporters in Congress and the media would like to see a shooting war between the United States and Iran start as soon as feasible. Having bought into the Israeli claim that the Islamic Republic represents an existential danger, Hillary Clinton recently described a potentially nuclear Iran as an "extraordinary threat." Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, describes the prospect as "calamitous." President Obama has reportedly asked Secretary of Defense Robert Gates to update the war plan to attack Iran. But propaganda and political posturing aside, what is the actual threat that Iran poses?

There are two principle areas where Iran interacts with American interests. The first is the alleged nuclear weapons program coupled with Tehran’s development of ballistic missiles that would be able to deliver the nuclear warheads to a target. There is an intense debate over whether Iran is developing nuclear weapons at all, with the Israelis and their allies insisting that they are and demanding that Tehran not be allowed to enrich uranium for any purpose. But the most authoritative study of the issue, the National Intelligence Estimate of December 2007, reported that Iran suspended its nuclear weapons program in 2003 and there are no signs that it has been restarted. The most recent study, appearing on May 21, carried out by a team of Russian and American scientists working for the Brussels-based EastWest Institute, looked at both the nuclear weapons issue and also the ballistic missile program. It concluded that Iran could build a simple nuclear device in one to three years only if it kicked out UN inspectors and dedicated itself to a weapons program. It would take five more years to be able to make the weapon small enough to fit onto a ballistic missile.

The report also noted that Iran would be unlikely to use a nuclear weapon, even if it had one, because of the threat of retaliation. As the report put it, the U.S. and Israeli nuclear arsenals guarantee that Tehran’s decision to use a nuclear weapon would mean that Iran would cease to exist immediately thereafter. The examples of India-Pakistan and the Cold War are cited as evidence that two adversaries having nuclear weapons actually decreases the likelihood that they might be employed because the weapons then become deterrents. Their use would devastate both sides.

But what about the oft-repeated argument that if Iran had nuclear weapons it might give them to terrorists? This is the ultimate "what if" red herring argument, like the hypothetical ticking bomb that justifies torture. It supposes two things: first, that Iran is in fact actively developing a weapon, and second, that it would be willing to lose control over the device by handing it to a terrorist for use. It also assumes that Iran is essentially both irrational and suicidal. It only works if Iran could hand over a weapon anonymously and avoid retribution. This would not be possible, as a nuclear device has characteristics that give it a very specific footprint, meaning that the attribution to Iran would take place and obliteration would follow, just as if Iran had used the weapon itself.

Iran’s other area of entanglement with the United States is through its neighbors, Iraq and Afghanistan, both of which are home to large numbers of American soldiers and both of which have large, active insurgencies. It has been alleged by U.S. military authorities and Congress that Iran is arming, training, and funding the insurgencies in both countries. This allegation has been given emotional form by Sen. Joe Lieberman and others who hope to demonstrate that Iran is already at war with the U.S. by claiming that Iran is "killing American soldiers."

The allegations regarding a perfidious Iran supplying lethal weapons to insurgents started in 2004 and appeared most recently on May 19, but they are all similar in that they suppose that when an Iranian-made weapon is in an insurgent’s hands it must have been put there by the Iranian government. In fact, Iranian weapons constitute only a small percentage of weapons in Iraq and even fewer in Afghanistan. There is no real evidence that the weapons, most of which come from stocks sold on the international arms market, are part of an Iranian government program. And the lack of evidence is not due to any lack of trying. The U.S. has been looking for an Iranian smoking gun for the past five years and has yet to find it.

Iran undeniably has an interest in developments among its neighbors, including Afghanistan and Iraq, but the interest is more to maintain stability than to stir up trouble. It would undoubtedly like to see the U.S. leave the region, but its government clearly recognizes that ending the American presence is currently not on the agenda. Iran is if anything an enemy of al-Qaeda and the Taliban, the two groups that Washington is itself fighting. It offered to help the United States in Afghanistan after 9/11 and has also attempted to come to a comprehensive settlement with the U.S. over all outstanding regional issues, an offer made in 2003 that was rejected by the Bush administration. There is no evidence that Iran is seeking to destabilize any of its neighbors or that it seeks war with anyone, Israel included.

One must conclude that Iran does not plausibly threaten the United States with its weaponry, army, or foreign policy. That is not to endorse Iran’s government or president, but merely to put the issue into perspective. Iran is involved in the affairs of its neighbors, but it would be a stretch to describe that engagement as interference. Allegations that it is actively supporting groups that are killing Americans are not supported by available evidence. The U.S., in short, has no vital interest at stake to justify a war and should resist at all cost Israel’s efforts to bring about a conflict that it believes to be in its own interests but that would hardly be good for the United States. If President Obama wants to do what is right for both the American and Iranian people, then he will look carefully at the relationship and announce that he is taking the military option "off the table."