NEW YORK – On a visit to the Pakistani capital Islamabad in 2006, Defense Secretary Chuck Hagel, then a Republican senator from Nebraska, warned that “a military strike against Iran, a military option, is not a viable, feasible, responsible option.”

Hagel reiterated that view in November 2007 in a speech to the Center for Strategic and International Studies, a Washington think tank. “The answer to dealing with Iran will not be found in a military operation,” he cautioned.

And it isn’t just then-senator Hagel.

“We’ve thought about military options against Iran off and on for the last 20 years,” former top White House counterterrorism official Richard Clarke admitted that same year, “and they’re just not good, because you don’t know what the endgame is. You know what the first move of the game is, but you don’t know what the last move of the game is.”

That was six years ago, but it’s a view that hasn’t changed in much of Washington. American politicians regularly threaten Tehran with severe consequences for its pursuit of nuclear weapons, and habitually announce that “all options are on the table.” But privately, many concede there is little stomach in the US for yet another Middle Eastern war that could sink the country down a rabbit hole of unintended consequences and commitments.

It’s not that American leaders and planners, even the “realists” among them, disagree with Israel about the dangers posed by a nuclear Iran.

As Hagel himself noted in that 2007 speech, during what may have been his most skeptical and realist period, “In the Middle East of the 21st century, Iran will be a key center of gravity… and remain a significant regional power. The United States cannot change that reality….

“[But] to acknowledge that reality in no way confuses Iran’s dangerous, destabilizing and threatening behavior in the region. Our differences with Iran are real. Iran is a state sponsor of terrorism and continues to provide material support to Hezbollah and Hamas. The president of Iran publicly threatens Israel’s existence and is attempting to develop the capacity to produce nuclear weapons. Iran has not helped stabilize the current chaos in Iraq and is responsible for weapons and explosives being used against US military forces in Iraq.”

Iran is bad news, American leaders acknowledge. But so is the possible fallout from any military strike.

And they’re right. A military strike against Iran’s nuclear program could elicit a massive retaliation and drag the region into one of the uglier wars it has known in a while. If that happens, the US expects to face hundreds of Iranian rockets smashing into US naval vessels and bases in the Persian Gulf; terror attacks by Iran’s proxies, especially Hezbollah, on US and allied targets around the world; a costly disruption in the global oil supply, both because Iran’s oil would be knocked off the market and because Iran would likely try to target oil production around the Gulf; and massive efforts by Tehran to inflame and destabilize regional allies and governments, from the Gulf states to Iraq to Lebanon and Gaza.

That’s a worst-case scenario, to be sure, but American defense planners state openly that they do not know what Iran’s reaction might be, and a regime so attacked might feel both the need and the political opportunity — domestic opposition would likely evaporate in the face of an attack on the Iranian homeland — to respond forcefully.

As Israel continues to demonstrate it has the military capability, the intelligence and the will to carry out dramatic operations, American confidence may grow, and American willingness to take the heavy risk of war may grow with it.

Yet even that terrible scenario emphasizes to Israeli leaders — who largely believe that diplomatic efforts can delay but ultimately not replace the need for a military solution — that the roots of American resistance to a strike are not principled or strategic; they’re tactical.

If American worries about the fallout could be assuaged, if the regime in Teheran could be shown to be militant in rhetoric but either incapable or unwilling to turn such an attack into a full-blown war, then the most significant barrier to an Israeli strike — the lack of American support — would be removed.

Over the past few years, Israel has planned, trained, and implemented – according to foreign sources, of course – audacious and sophisticated strikes against Iranian assets, from the “Karine A” weapons ship, to armaments convoys in Sudan (at a distance from Israel farther than many potential Iranian targets), to Syria’s nuclear reactor and the latest strikes against Syrian installations and weapons convoys. In Iran itself, Israel is widely credited with infiltrating and repeatedly sabotaging the nuclear program, with centrifuges breaking down, computer viruses disrupting operations on a vast scale, installations suffering damaging explosions, and key nuclear scientists being mysteriously assassinated.

Before and after satellite images of the Syrian nuclear reactor at al-Kibar, which was reportedly struck by Israel in 2007 (AP/DigitalGlobe)

Before and after satellite images of the Syrian nuclear reactor at al-Kibar, which was reportedly struck by Israel in 2007 (AP/DigitalGlobe)

After each alleged Israeli strike against Iran’s nuclear program and weapons smuggling, global expert opinion declares in unison that besides the obvious military benefits, the operation carries a “message” for Iran.

But these operations also carry a message for the uneasy West, and especially the United States: Iran is vulnerable to attack, and the consequences are minimal.

After a daring, 1,800-kilometer (1,100 mile) strike in Sudan in 2009, a few Arab states complained — quietly — about Israeli trespassing. After the 2007 strike against the Syrian reactor, the loudest condemnation came from North Korea, inadvertently drawing attention to itself as the source of the expertise and equipment for the Syrian installation.

Israel would be hard-pressed to carry out a strike on a target as distant, well-protected and widely scattered as the Iranian nuclear program without US knowledge and assistance. A successful operation might require not only American willingness to absorb the blowback, but active American help, or at least coordination.

For the Israel Air Force and special ground forces that conducted the long-range operations of recent years, a strike in Syria amounts to a 100-meter sprint. Iran’s nuclear program, 1,600 kilometers (1,000 miles) away and with several major and dozens of minor potential targets, is a marathon. As with a marathon, success will require special training, special logistical capabilities and an especially high tolerance for pain.

The strikes in Syria won’t be enough to convince the Americans that a viable military option exists for Iran. Iran’s failure to lash out over strikes on Syria or Sudan is not indicative of its response to attacks on its own soil. But as Israel continues to demonstrate it has the military capability, the intelligence and the will to carry out dramatic operations, American confidence in the potential success of such operations may grow, and American willingness to take the heavy risk of war may grow with it.

This weekend’s strikes on Syria, beyond their immediate military benefit and the obvious message to Assad, Hezbollah and Iran, are a message to Washington as well. To quote a different leader who once delivered a rather similar message to a skeptical American ally: “Give us the tools and we will finish the job.”