A few weeks ago, in discussing how Hezbollah might respond to an Israeli strike on Iran’s nuclear program, I mentioned that both the United States and Hezbollah are more or less held hostage to the drama unfolding between their respective allies. For the United States, part of that dynamic includes the uncertainty it faces concerning whether or not Israel will in fact strike Iran’s nuclear program and, if so, when.

The United States is Israel’s closest ally in the world. The United States has provided Israel an average of $3 billion in grants, almost all of it military aid (.pdf), each year for the past three decades, making Israel by far the largest recipient of U.S. aid since the end of World War II.

Despite all that largesse, the United States has no idea whether or not its close ally will attack Iran -- an action that could have enormous consequences for U.S. interests in the region. Some might argue that this uncertainty represents a diplomatic failure on the part of the United States and that U.S. officials should use U.S. aid to Israel to effect closer policy coordination. For now, though, I want to focus on the intelligence failure that this uncertainty represents.

In his book “Why Intelligence Fails,” Robert Jervis examines two high-profile U.S. intelligence failures: the failure to anticipate the fall of the shah in Iran and the failure to determine whether or not Saddam Hussein had weapons of mass destruction prior to the war in Iraq in 2003. Jervis notes that intelligence organizations are normally asked to answer questions regarding both capability and intent. Questions regarding capability are usually easier to answer, which is partly why the failure on weapons of mass destruction was so galling.

Questions regarding intent, meanwhile, are much more difficult, and for several reasons. First, unlike answering a question about military hardware, determining a leader’s intent is akin to explaining what is going on inside someone’s mind -- not the easiest thing to do, even with the most transparent of leaders.

Second, people change their minds and often do not communicate that they have done so. We all rely on past behavior to predict the future, but this can get us into trouble when trying to divine intent.

Third, people sometimes make poor decisions that intelligence analysts would not themselves have made. One of the reasons the United States failed to anticipate the Cuban Missile Crisis, Jervis notes, is that the United States failed to imagine that Nikita Khrushchev could have made such a terrible mistake.

Fourth, people often obscure their intentions on purpose. Deception is a fact of life for those collecting and analyzing intelligence, even if at times those acts of deception make little sense in the mind of the analysts themselves. One of the reasons the United States failed to predict whether or not Iraq had weapons of mass destruction, Jervis argues, is that Saddam Hussein rather illogically kept up the appearances of having a weapons program. The illusion of such a program had little hope of deterring the Iranians and indeed helped precipitate the U.S. invasion of Iraq that deposed Saddam. Nonetheless, Saddam felt the deception was worth it until the end.

Israel has reason to deceive the United States regarding its own intentions. The Obama administration has consistently delivered two clear messages to Israel’s leaders regarding Iran’s nuclear program: First, Israel should not contemplate a strike on the program; second, the United States takes responsibility for deterring Iran or, in the event that fails, retarding the program itself. Many in the U.S. government, including both in the administration and the U.S. military, would be livid with Israel’s leaders if they unilaterally attack Iran. So Israel, if it indeed decides to act on its own, would have reason to keep that intent hidden from the United States.

Israel might also want to make the United States think it will attack Iran in order to precipitate more-aggressive U.S. action. Israel has a capability problem regarding any potential attack on Iran -- namely, it lacks the long-range stealth bombers and in-flight refueling capability that the United States has. As a result, an Israeli air strike on Iran might well involve the entire Israeli Air Force, which would then need to hurry back to Israel to prepare to strike targets in Lebanon and Gaza in the event of a counterattack by Iranian proxy groups. For reasons of capability alone, Israel would much prefer the U.S. Navy and Air Force to carry out a military operation against Iran.

An Israeli decision to strike Iran anytime in the near future will likely be taken by two men: Prime Minister Benjamin Netanyahu and Defense Minister Ehud Barak. Technically, any decision to attack Iran would be made by the security cabinet, one member of which recently expressed doubt that a strike would help Israel. But if the prime minister and the minister of defense opt for a strike, they will likely bring the rest of the cabinet along.

Much time and energy has been spent examining Netanyahu’s character, the way he sees himself and his relationship with his hawkish father. The closest Israel-watchers I know, though, spend more time trying to determine what the old commando, Barak, is thinking. Unlike Netanyahu, Barak has the national security credentials to bring a reluctant security cabinet along.

In an ideal world, of course, Israel would care most about what its closest ally thinks. And it does, to a point. But breaking a pattern established for decades, in which Israeli leaders suffered politically for having poor relations with an American president, Netanyahu has gained political capital from standing up to U.S. President Barack Obama on settlement construction in the West Bank. And whatever Israeli leaders hear from the Obama administration and the U.S. military is tempered by what they hear from the U.S. Congress, where the rhetoric regarding Israel is such that one could be forgiven for not knowing which country was the generous benefactor and which the dependent ally.

I have no idea whether or not Israel will attack Iran. Nor do I know whether Ehud Barak and others believe Israel has the capability to do serious damage to Iran’s nuclear program and how they view the likely fallout from an attack.

My sense, though, based on conversations with Israeli leaders and Israel-watchers as well as years spent studying Israeli military operations and strategic thinking -- or what passes for strategic thinking in a country where domestic politics seems to determine everything -- is that Israel might be willing to roll the dice on an attack on Iran and, in effect, see what happens.

That gamble could have grave consequences for regional stability and U.S. interests. In the meantime, both the Obama administration and the U.S. military will struggle to determine whether or not Israel will strike -- and how they should respond if it does.

Andrew Exum is a senior fellow at the Center for a New American Security and teaches a course in low-intensity conflict at Columbia University's School of International and Public Affairs. He blogs at Abu Muqawama. His WPR column, Abu Muqawama, appears every Wednesday.

Photo: Iranian President Mahmoud Ahmadinejad (Photo by Daniella Zalcman, licensed under the Creative Commons Generic 2.0 Agreement) and Israeli Prime Minister Bejamin Netanyahu (World Economic Forum photo, licensed under the Creative Commons ShareAlike 2.0 Agreement).