Had Iran's alleged terror plot succeeded, the brazen assassination of a Saudi ambassador in Washington would have provoked American outrage and demands for immediate action far beyond what's under consideration. It's doubtful the attack would have sparked an all-out U.S.-Iran war.
If such an attack were clearly linked to Iran, it might prompt strikes against Iranian nuclear or military facilities.
The Obama administration says the conspiracy was linked to elements in the Iranian government, representing a dangerous escalation in an already extremely hostile relationship. The two countries are irrevocably split over issues such as Tehran's uranium enrichment activity, alleged support for al-Qaida and Taliban attacks against American soldiers, attempts to destabilize U.S. nation-building efforts in Iraq, and support for Hamas and Hezbollah militants fighting Israel.
Yet despite 32 years of animosity, the sides have avoided full-scale military conflict. That would be unlikely to change no matter how symbolically damaging the first international terror attack on U.S. soil since the Sept. 11, 2001, attacks would have been.
"You would want to start with putting sanctions on steroids," said James Woolsey, a CIA director under President Bill Clinton, who added that he would propose a "total secondary boycott" on Iran. "With the exception of food and medicine, any person, partnership or corporation in any country that does business with Iran in any form could not do business with the United States."
Woolsey said the U.S. would be wise to steer clear of military options. Even an air or naval blockade would risk a significant escalation in the conflict at a time when the U.S. could rally countries around the world for far tougher sanctions against the Islamic republic, he said.
Others said Washington would have to act tougher, with the most obvious target of retaliation being Iran's nuclear sites. Iran insists that its program is designed solely for peaceful energy production, while the United States and other governments suspect it is aimed at producing atomic weapons.
Had the terror plot worked, "the immediate question would have been whether you go after the nuclear program and set it back by several years," said John Hannah, who was national security adviser to Vice President Dick Cheney. He said such an approach would have far greater strategic effect than "the pinprick of lobbing 50 missiles at various sites."
Hannah said the attack as it was purportedly planned _ for a restaurant where Americans may also have been killed _ would demand a military response and that any American action could bring the countries closer to war. The U.S. should send a message to make sure Iran doesn't entertain similar plans in the future, he said, while "leveraging this unbelievable act of aggression" to deal with a problem that has been twisting American officials in knots for the last decade.
For now, the Obama administration is avoiding questions about what type of response a successful terror attack would have warranted.
"I think that's speculating on what might have happened had we not succeeded in disrupting this plot because of the excellent work and coordination between our law enforcement agencies and our intelligence agencies," White House press secretary Jay Carney said Wednesday.
"In this arena, we take no options off the table," Carney said. "But in dealing with Iran, we are clearly focused on working through economic measures, sanctions, as well as diplomatic measures, to isolate Iran. And we've had, we think, substantial success doing that."
State Department spokeswoman Victoria Nuland similarly declined to be drawn on what she termed "hypotheticals _ if X, then Y _ on the part of the United States." She said only that the killing would have amounted to a "massive act of terror" and "been not only deadly, but have had very dangerous international repercussions."
The "what if" question delves by nature into hypothetical assumptions, and that's partly why it is so hard for American officials and international security experts to get into. Answering it also can be self-defeating by telegraphing to Iranian or other would-be attackers the constraints on a U.S. policy response.
Still, it's an area that demands consideration if only to understand how the U.S. might respond to a similar scenario in the future. And it's a question the United States is asking of others.
Wendy Sherman, testifying before the Senate on Thursday to become one of Secretary of State Hillary Rodham Clinton's top deputies, said she had spoken by telephone earlier in the day with a foreign official and pushed him on the same hypothetical situation.
"Think about what your country needs to do and think about it in terms of what you would have done and what the international community would have done if indeed this had been successful," Sherman said she asked the unnamed official. "It would have been catastrophic in so many ways that I think we can't even begin to imagine."
Washington is tying the attack to Iran's elite Quds Force, which it has already blamed for some of the worst terrorist acts against U.S. troops overseas, including the 1996 Khobar Towers bombing that killed 19 Americans in Saudi Arabia. More recently it has been accused of smuggling long-range rockets into Iraq for use by Shiite militants, including in a June attack outside Baghdad that killed six American servicemen.
But none of these attacks was planned in the nation's capital.
Lawmakers are alarmed. Sen. Carl Levin, D-Mich., the chairman of the Senate Armed Services Committee, said the alleged plot might be an act of war, while Rep. Michael McCaul, R-Texas, who heads a homeland security House subcommittee, said it would be war if it were indeed sponsored by the Iranian government.
For the U.S., there are no direct corollaries to the alleged Iranian plot. American ambassadors to Afghanistan and Sudan were assassinated in the 1970s, the same decade a former Chilean ambassador to the U.S. was murdered by agents of Gen. Augusto Pinochet who blew up the ex-diplomat's car in the middle of Washington.
None of those instances prompted war, only legal and diplomatic repercussions.
Perhaps the best gauge of a likely response can be found in the U.S. reaction to the Iraqi plot to assassinate former President George H.W. Bush in 1993. Clinton, only five months into office after defeating Bush, ordered warships to fire 24 Tomahawk cruise missiles at Saddam Hussein's intelligence headquarters in Baghdad. By Iraq's count, eight people died.