Israeli attack on Iran would be complex operation - USA TODAY

"This would be way more sophisticated than anything that's ever been done before," said Charles Wald, a retired Air Force general who led the coalition air campaign in Afghanistan that helped topple the Taliban.

By contrast, Israel's strike on Iraq's Osiraq nuclear reactor in 1981 and an attack in Syria in 2007 were simpler operations that required Israel to hit a single above-ground target. Neither country had sophisticated air defense capabilities.

There would be nothing "surgical" in a strike on Iranian facilities, Wald said.

Iranians have learned from Israeli attacks in Syria and Iraq, Wald said. Iran's nuclear facilities are dispersed throughout the country, some of which are being hardened to withstand bomb blasts, said Colin Kahl, a Georgetown professor and former Pentagon official overseeing Middle East policy. Pilots would face a network of radar and anti-aircraft missiles designed to protect Iran's airspace.

Middle East analysts say it is difficult to predict precisely how any attack might unfold.

"The Israelis are extraordinarily creative," Kahl said. "Nobody knows exactly how they would do it."

The key challenges Israel would face if it launched an attack:

Range

Israeli pilots would be near or exceed the maximum range of their U.S.-built F-15s and F-16s, depending on the route they took and their speed and payload.

Wald said the Israelis would either have to use aerial refueling or land somewhere en route to refuel. It's not known whether any country would provide permission or whether Israel could set up a covert refueling facility in the desert.

Aerial refueling has its own set of challenges. Israel's air force has limited refueling capacity, and if it launched any of its four KC-130 tankers, it would have to commit fighter planes to protect them, putting a further strain on resources, said Scott Johnson, an analyst at IHS Jane's, a defense consulting firm. Israel has about 350 F-15s and F-16s.

Flying over Iraq is the most direct route for Israeli pilots. Since the U.S. withdrawal, Iraq is not capable of effectively protecting its airspace, which potentially would give Israel a way to reach Iran while maintaining an element of surprise.

Air defenses

Israeli aircraft could probably penetrate Iranian air defenses, but Israel would need to commit additional aircraft to jam radars and in other ways neutralize Iran's radar and missile systems, analysts say.

"They're not using wax pencils on glass," Johnson said of Iranian air defenses. "They have updated computerized modern air defenses."

Iran doesn't have the latest systems, said Wald, a military analyst at the Bipartisan Policy Center, a think tank. In 2010, Russia canceled a planned sale to Iran of sophisticated S-300 surface-to-air missiles that would have significantly upgraded Iran's anti-aircraft defenses.

Bombs

Israel has large bombs capable of penetrating bunkers, but some analysts say they need more sophisticated munitions to help knock out some of the well-protected facilities.

Israel has the U.S.-built GBU-28 bunker busters, 5,000-pound bombs capable of blasting hardened targets. In a recent report, the Bipartisan Policy Center advocated the United States provide Israel with the more sophisticated GBU-31.

Analysts say timing on a strike would be critical, since a lengthy operation would raise the likelihood of U.S. opposition and could trigger a wider conflict.

"They will probably only get one strike," said Anthony Cordesman, an analyst at the Center for Strategic and International Studies.

Wald says the campaign would require more time. "If you really wanted to do this right, you're talking a few weeks probably," he said.

The United States should be prepared for an Iranian counterstrike, Wald said. Iran has medium-range missiles that could reach Israel, Kahl said.

There are other ways Iran could strike back. Iran's navy could interfere with commercial shipping in the narrow Strait of Hormuz, disrupting the world's oil supplies. In 2009, about 17% of all oil traded worldwide went through the narrow strait, according to the Energy Department.

Iran would probably use its surrogates, Hamas in Gaza and Hezbollah in Lebanon, to attack Israel, analysts say. "You've got to be ready for that," Wald said.