Last week, The Associated Press reported that officials in Israel — all of whom spoke on condition of anonymity because they were not authorized to discuss Iran — were concerned that the measures, while welcome, were constraining Israel in its ability to act because the world expected the effort to be given a chance.
Even a limited Israeli operation could well unleash regionwide fighting. Iran could launch its Shihab 3 missiles at Israel, and have its local proxies, Hezbollah in Lebanon and Hamas in the Gaza Strip, unleash rockets. Israel's military intelligence chief, Aviv Kochavi, warned last week that Israel's enemies possess some 200,000 rockets.
While sustained rocket and missile fire would certainly make life uncomfortable in Israel, Barak himself has said he believes casualties would be low — suggesting it would be in the hundreds.
Iran might also try to attack Western targets in the region, including the thousands of U.S. forces based in the Gulf with the 5th Fleet.
An Israeli attack might have other unintended consequences. A European diplomat based in Pakistan, permitted to speak only under condition of anonymity, said that if Israel attacks, Islamabad will have no choice but to support any Iranian retaliation. That raises the specter of putting a nuclear-armed Pakistan at odds with Israel, widely believed to have its own significant nuclear arsenal.
To some, the greatest risk is to the moribund world economy.
Analysts believe an Israeli attack would cause oil prices to spike, since global markets so far have largely dismissed the Israeli threats and not "price in" the threat. According to one poll conducted by the Rapidan Group, an energy consulting firm in Bethesda, Maryland, prices would surge by $23 a barrel. The price of oil settled Friday at $97.84 a barrel.
"Traders don't believe there's anything but bluster going on," said Robert McNally, president of Rapidan and an energy adviser to former President George W. Bush. "A potential Israeli attack on Iran is different than almost every scenario that we've seen before."
McNally said Iran could rattle oil markets by targeting oil fields in southern Iraq or export facilities in Saudi Arabia or Qatar — and withhold sales of its own oil and natural gas from countries not boycotting.
Iran also could attempt to carry out its biggest threat: to shut the Strait of Hormuz, a strategic waterway through which a fifth of the world's oil passes. That could send oil prices soaring beyond $200 a barrel. But analysts note Iran's navy is overmatched.
If a surge in oil prices proved lasting, financial markets would probably plummet on concerns that global economic growth would slow and on the fear that any conflict could worsen and spread.
For the U.S. economy, higher gasoline prices would likely result in lower consumer spending, which accounts for 70 percent of U.S. economic activity. That could have devastating consequences for an incumbent president seeking re-election.
Nick Witney, former head of the EU's European Defense Agency, said "the political and economic consequences of an Israeli attack would be catastrophic for Europe" since the likely spike in the price of oil alone "could push the entire EU, including Germany, into recession."
He said this could lead to "messy defaults" by countries like Greece and Italy, and possibly cause a collapse of the already-wobbly euro. Witney, a senior fellow at the European Council on Foreign Relations, added that "the Iranians would probably retaliate against European interests in the region, and conceivably more directly with terrorism aimed at Western countries and societies."
Oil disruptions or higher oil prices will also dent growth in Asia. China, India, South Korea and Japan all buy substantial amounts of Iranian crude and could face temporary shortages.
China's fast-growing economy, which gets 11 percent of its oil from Iran, has urged all sides to avoid disrupting supplies. Any impact on China's economy, the world's second-largest, could send out global shockwaves if it dented Chinese demand for industrial components and raw materials.