Israeli Prime Minister Benjamin Netanyahu’s call for the United States to declare “red lines” for Iran and its nuclear program makes it even harder for the Obama administration to walk the line between calming Israel and increasing the pressure on Iran. As Washington considers its responses -- and anticipates how Iran would respond in turn -- the risk of terrorism will loom large for both Israel and the United States.
Terrorism related to Iran’s nuclear program has already begun. Indeed, perhaps the most surprising aspect of the suspected Iranian-orchestrated terrorist attack in July that killed five Israelis and a local bus driver in Bulgaria is that it generated little surprise or reaction in Israel. Israel's former national security advisor, Uzi Arad, pointed out that Iran was simply responding to Israel's covert campaign against Tehran: "Anybody with eyes in their head can see we are in the middle of an escalation orchestrated by various elements, and where occasionally, we are the instigating side."
This "shadow war" between Israel and Iran has created an escalatory dynamic as the Bulgaria attack indicates, with Iran feeling compelled to respond to what it sees as Israeli aggression. Although specifics are steeped in secrecy, Israel is blamed (or lauded, depending on where you stand) for killing Iranian nuclear scientists, sabotaging an Iranian missile facility, releasing a computer virus that crippled Iranian centrifuges, and killing noted terrorist Imad Mughniyeh, the Hezbollah operations commander who worked closely with Tehran and who was responsible for the deaths of hundreds of Americans when Hezbollah bombed the U.S. Embassy in Beirut and U.S. Marine Barracks in 1983.
Terrorism, well before Bulgaria, was Iran's response to such Israeli actions. In 2012 alone, Iran has been linked to attempted attacks in Azerbaijan, Cyprus, Georgia, India, Kenya, and Thailand. In October 2011 the United States disrupted a plot to kill the Saudi ambassador in Washington by bombing the restaurant where he often ate lunch. Had the bomb gone off as planned, it would have killed many Americans dining there, too. The question, therefore, is not whether Iran will respond to further provocation -- including the ultimate provocation of air strikes on its nuclear facilities -- but how, and whether Iran's response should alter the U.S. and Israeli calculus.
In considering this question, it's important to realize that terrorism is both Iran's best option for striking back and its only one. When they feel under assault, Iran's leaders want to prove to their population that they are fighting back. The regime is sensitive to any humiliation and has a strong belief in revenge. Anger is particularly intense within key elite audiences (particularly the Islamic Revolutionary Guard Corps, which both protects the regime against domestic opponents and leads its covert operations abroad). Perhaps most important, for all its bluster, Iran is a weak country: its conventional military forces are poorly armed and weakly trained. Economically, Iran is reeling from increasingly tight sanctions, and its ideology holds little appeal -- even in Iran itself. Iran, however, has developed a robust intelligence and paramilitary apparatus, and in the past it has conducted or attempted attacks, at times with its ally the Lebanese Hezbollah, in Europe, Asia, Latin America, and Africa, as well as the Middle East. For Iran, terrorism works.
So, if Israel or the United States took the war out of the shadows and conducted a direct military strike on Iran's suspected nuclear facilities, the Iranian terrorist response would be considerable. We could expect terrorist attacks around the world -- Iran and Hezbollah have shown a presence on every inhabited continent. In addition, Iran would be particularly likely to step up support for anti-U.S. forces in Afghanistan and elsewhere in its neighborhood. Tehran would also use the limited al Qaeda presence in Iran and its ties to Sunni jihadists to try to strike the United States and its allies: the relationship is troubled, but Iran has influence over al Qaeda, and now would be the time for Tehran to call in favors. The scope and scale of the response would depend on the level of casualties from any attack and the political circumstances of the regime in Tehran at the time the attack occurred. An attack that caused many Iranian casualties and was proven to be successful (and thus embarrassing for Iran's leaders), particularly if it came at a time when the Iranian regime felt politically weak, could lead to terrorist attacks on U.S. and Israeli facilities and personnel around the world, including on U.S. soil.
Still, the threat of U.S. retaliation for such retaliation would make Iran's leaders careful not to let escalation get out of hand. America's conventional might has long moderated Iran's behavior because Tehran knows its forces are no match for those of the United States. Iran toned down its anti-U.S. terrorism after orchestrating the 1996 Khobar Towers bombing. The quite real specter of a U.S. military strike and more comprehensive sanctions probably sobered Iran's leaders.
That could change, however, if Iran acquired a nuclear weapon. Some scholars have argued the theoretical point that, in general, nuclear weapons make states more cautious as they fear the catastrophic escalation that a nuclear crisis could bring. More likely, though hardly inevitable, is that Tehran might become emboldened by a nuclear weapon since it would then have the ability to threaten a devastating response should it be attacked with conventional forces. This "umbrella" would then enable Iran to be more aggressive supporting substate groups like Hezbollah or opposition forces against various Arab enemies.