The enormous costs involved in engaging U.S. forces against Iran, both human and materiel, should not be bandied about lightly.

(This story originally appeared on March 28, 2015, more than three years before Pres. Donald Trump ended the Obama-era deal preventing Iran from obtaining nuclear weapons.)

Iran hawks are playing with fire. We are close to a nuclear deal with Iran, but opponents continue to step up attacks aimed at torpedoing efforts to reach a settlement. They insist that we must walk away from the negotiating table, and that there’s a better deal to be had.

That belief is a fantasy.

The reality is that if negotiations with Iran fail, the wreckage will leave the United States without any good options. “If we undermine negotiations now, we’ll have only two choices — Accept the reality of an Iranian nuclear bomb, or use military force to attack Iran’s nuclear program,” former Sen. Carl Levin wrote in a recent op-ed for U.S. News & World Report.

There is hardly a nation in the world that wants a nuclear Iran. But the United States should only consider a war with Iran to be a last resort. “If you think the war in Iraq was hard, an attack on Iran would, in my opinion, be a catastrophe,” former Defense Secretary Robert Gates said in 2012.

Furthermore, he added that such a quixotic attack would only “make a nuclear-armed Iran inevitable, [as] they would just bury the program deeper and make it more covert.”

Yet the reality of this no-win scenario has done little to deter hawks, both in and out of Congress, from continued attempts to undermine negotiations. Arkansas Sen. Tom Cotton’s letter, signed by 46 of his Republican colleagues, is only the most recent example of their continued campaign of political brinkmanship.

Even more worrisome though, is the cavalier attitude toward the use of U.S. military force that underlies this approach.

In his recent op-ed for The New York Times, former Bush administration official John Bolton backed up the idea of using U.S. military force against Iran.

“The inconvenient truth is that only military action like Israel’s 1981 attack on Saddam Hussein’s Osirak reactor in Iraq or its 2007 destruction of a Syrian reactor, designed and built by North Korea, can accomplish what is required,” he wrote.

“Time is terribly short, but a strike can still succeed,” Bolton added. “Such action should be combined with vigorous American support for Iran’s opposition, aimed at regime change in Tehran.”

These comments echo Cotton’s statements from earlier this month. “Israel struck Iraq’s nuclear program in 1981 and they didn’t reconstitute it,” Cotton said.“Rogue regimes have a way of getting the picture when there is a credible threat of military force on the table.”

Both Bolton and Cotton’s accounts of the strikes on Iraq in 1981 are completely wrong.

Those strikes actually drove the program underground, where it expanded. This is just what Gates warns would happen with Iran. As Deputy National Security Advisor Colin Kahl wrote in 2012, “new evidence suggests that Hussein had not decided to launch a full-fledged weapons program prior to the Israeli strike.”

“By demonstrating Iraq’s vulnerability, the attack on Osirak actually increased Hussein’s determination to develop a nuclear deterrent and provided Iraq’s scientists an opportunity to better organize the program. The Iraqi leader devoted significantly more resources toward pursuing nuclear weapons after the Israeli assault. As [political scientist Dan] Reiter notes, ‘the Iraqi nuclear program increased from a program of 400 scientists and $400 million to one of 7,000 scientists and $10 billion.’”

More importantly, these sentiments are reminiscent of the Bush administration’s failed policy toward Iran in the early 2000s. When approached with deals that would have seen all of Iran’s enriched uranium converted into fuel rods — and would have capped the program with some 100 odd centrifuges — the Bush administration balked.

Vice President Dick Cheney even once said, “We don’t negotiate with evil; we defeat it.” The results? Negotiations collapsed and Iran went from only a few installed centrifuges at the beginning of the Bush administration to about 6,000 by the end.

While many conservatives are quick to spurn negotiations with Iran, they seem to have done very little in the way of analyzing what a war with Iran would actually look like. Maybe they need a reminder.

It would neither be quick nor painless. As former Brookings Institution fellow Noah Shachtman described in 2012, it would be a major major military action, with little chance of lasting success.

“Setting back Iran’s nuclear efforts will need to be an all-out effort, with squadrons of bombers and fighter jets, teams of commandos, rings of interceptor missiles and whole Navy carrier strike groups — plus enough drones, surveillance gear, tanker aircraft and logistical support to make such a massive mission go. And all of it, at best, would buy the U.S. and Israel another decade of a nuke-free Iran.”

Even a limited strike by U.S. air and naval forces would be massive, according to Anthony Cordesman of the Center for Strategic and International Studies.

“It it is not a simple mission of bombers flying in and out of Iran, this is a complicated Offensive Air Strike that will involve many aircraft, each with its own role, such as Combat Aircarft [sic] whose role is to suppress enemy air defenses along the way, aircraft that fly fighter escort with the bombers, aircraft that carry specialized electronic warfare equipment to jam enemy radars and communications., plus probably air-to-air refueling along the way in and out of Iran.”

Even then, Cordesman added, “depending on the forces allocated and duration of air strikes, it is unlikely that an air campaign alone could alone terminate Iran’s program. The possibility of dispersed facilities complicates any assessment of a potential mission success, making it unclear what the ultimate effect of a strike would be on Iran’s nuclear facilities.”

Further complicating matters, U.S. military forces would not be able to simply focus on striking Iranian nuclear targets. They would also have to safeguard the Strait of Hormuz — a narrow waterway connecting the Gulf of Oman to the Persian Gulf — through which some 20 percent of the world’s oil passes, as well as countless other U.S. and allied strategic assets in the area.

Indeed, even a temporary closure of the strait through Iranian deployment of mines, mini-subs, shore-to-ship missile batteries and patrol boats could have a serious effect upon the world economy.

The Federation of American Scientists estimates that the “the rough effects of U.S. [military] action against Iran on the global economy — measured only in the first three months of actualization — [could] range from total losses of approximately $60 billion on one end of the scale to more than $2 trillion to the world economy on the other end.”

All in all, a U.S. or coalition attack against Iran now would be like setting off a bomb in a gunpowder factory. As Cordesman noted, any “military strike [against Iran] could be destabilizing for the entire Middle East region and potentially generate a nuclear weapons race in that part of the world.”

War with Iran is no joke. Critics of a deal with Iran should not treat it like one. A breakdown in negotiations will have serious repercussions for the Middle East and U.S. foreign policy. That being the case, lawmakers should be more careful when threatening to use U.S. military force.

The enormous costs involved in engaging U.S. forces against Iran, both human and materiel, should not be bandied about lightly.

As Levin wrote, “We owe it to our friends and allies in the region, and to our men and women in uniform who might have to risk their lives if diplomacy fails, to give negotiations every chance to succeed.”

We should listen to his advice.

Geoff Wilson is a Research Associate at Ploughshares Fund, a global security foundation. He has authored articles for The Huffington Post, Defense One and War on the Rocks.

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