Israeli attack on Iran could entangle U.S.

WASHINGTON -- An Israeli pre-emptive attack on Iran's nuclear sites could draw the U.S. into a new Mideast conflict, a prospect dreaded by a war-weary Pentagon wary of new entanglements.

That could mean pressing into service the top tier of American firepower -- warplanes, warships, special operations forces and possibly airborne infantry -- with unpredictable outcomes in one of the world's most volatile regions.

"Israel can commence a war with Iran, but it may well take U.S. involvement to conclude it," says Karim Sadjadpour, a Middle East specialist at the Carnegie Endowment for International Peace.

An armed clash with Iran is far from certain. Diplomacy backed by increasingly tough economic penalties is still seen by the United States and much of the rest of the world as worth pursuing for now, not least because the other options -- going to war or simply doing nothing -- are considered more risky.

Israel, however, worries that Iran soon could enter a "zone of immunity" in which enough of its nuclear materials are beyond the reach of Israeli air power so that Iran could not be stopped, or perhaps could be stopped only by superior American firepower.

Michael O'Hanlon, a defense analyst at the Brookings Institution, sees a chance that the U.S. could largely stay out of the fight if Israel struck first. If Iran's air defenses managed to knock down an Israeli fighter pilot, however, U.S. special operations forces might be sent to rescue him, he said.

If the U.S. spotted Iran preparing to fire a ballistic missile at Israel in a retaliatory act, "it's possible we would decide to take that missile out," O'Hanlon said.

Uncertainty about Iranian retaliation, as well as the cascade of potential consequences if the U.S. got drawn into the conflict, is at the core of U.S. officials' rationale for publicly casting doubt on the wisdom of Israeli military action now.

Depending on the type and scale of the Iranian reaction to an Israeli strike, and whether it included attacks on U.S. forces or bases, President Barack Obama would be under enormous political pressure to come to Israel's aid. His prospective Republican challengers have already tried to portray Obama as insufficiently loyal to Israel and overly tolerant of Iran.

Obama could decide to provide Israel with extra missile defense systems, such as the Patriot, to help defend its cities. He could choose a more aggressive course, ordering follow-up airstrikes on Iranian targets such as military bases and its remaining nuclear facilities.

The U.S. has two aircraft carriers, the Abraham Lincoln and the Carl Vinson, and many other warships near Iran's shores. There is also a wide array of U.S. warplanes at land bases on the Arabian Peninsula, and thousands of troops in Kuwait. It also has special operations forces in Afghanistan.

Obama has not ruled out using force to stop Iran from building a bomb. But his administration, joined by many allied nations, has counseled Israel to hold off. Several senior administration officials have been to Israel in recent days to emphasize caution, including Obama's national security adviser, Tom Donilon.