Adlai Stevenson once advised that "to act coolly, intelligently and prudently in perilous circumstances is the true test of a man — and also of a nation." In the face of Iran's potential for becoming a nuclear weapons state and a threat to Israel, U.S. leaders would be smart to follow Stevenson's advice and act prudently and intelligently.
There is little doubt that a nuclear-armed Iran would pose dangerous challenges to U.S. interests and security, as well as to the security of Israel. There is no question of the seriousness of the problems presented by Iran's nuclear program or the need to consider the use of military force as a last resort.
An attack on Iran could set back Iran's ability to build a nuclear weapon but not stop the program permanently. Barring a decision to deploy large numbers of troops on the ground, we doubt that U.S. military attacks from the air — plus other means, such as drones, covert operations and cyberattacks — could eliminate Iran's capability to build a nuclear weapon, bring about regime change or force Iran to capitulate to U.S. demands.
U.S. and Israeli intelligence communities agree that Iran's leaders have not yet made a decision to build a nuclear bomb. The official U.S. government position is that if Iran were to produce weapons-grade enriched uranium and build a weapon, the military option must be considered. Defense Secretary Leon Panetta said the U.S. would have "a little more than a year to take the necessary action" should Iran decide to move quickly toward having a nuclear weapon.
An American decision to attack Iran could demonstrate its credibility as an ally of other nations in the region and would derail Iran's nuclear ambitions for several years. An attack would also underscore America's full commitment to nonproliferation as other nations contemplate moves in that direction.
There are also costs that are more difficult to estimate because of the uncertainties about the scale and character of Iran's reaction and the impact an attack would have elsewhere in the region. Iran would probably retaliate directly while pursuing an asymmetrical response, such as use of terrorism, covert operations or drawing on surrogates such as Hezbollah. We could expect a spike in the price of oil, and the global economy would probably suffer for as long as the hostilities continued.
Military action could also escalate a regional war involving Syria, Hezbollah, the Palestinians as well as other Arab states and terrorist groups. A larger war in the region would obviously do damage to Israel's position and set back U.S. interests and objectives in the Middle East. A military strike could speed an Iranian decision to build a nuclear weapon, destabilize Arab nations already seeking a new footing and create opportunities for extremist groups to attract new recruits.
In view of this profoundly troubling dilemma the U.S. faces in how to respond to Iran's challenges, we joined a group of more than 30 prominent former defense and foreign policy experts in supporting a recently released report, "Weighing the Benefits and Cost of Military Action Against Iran." In a time marred by hyper-partisan rhetoric, we believed the American people deserve a fact-based discussion of the objectives, costs, benefits, timing, capabilities and exit strategy that should govern any decision to use military force.
Thomas Pickering was a former undersecretary of state for political affairs from 1997 to 2000 and served as U.S. ambassador to Russia, Israel, Jordan and the United Nations. Gen. Anthony Zinni is a retired four-star Marine general and commander of U.S. Central Command from 1997 to 2000. Jim Walsh, an expert in international security and nuclear weapons, is a research associate at the Massachusetts Institute of Technology's security studies program.