WASHINGTON (AP) — Proposed new U.N. penalties on Iran fall far short of what it would take to cripple the Islamic republic's nuclear program, and even military strikes might merely delay Iran's nuclear ambitions.

Ultimately, the only country capable of stopping Iran is Iran.

Knowing this, the Obama administration figures that economic pressure is worth a stab. Officials hope that enough added pressure might convince Iran that benefits of the bomb are not worth the costs.

But through three previous rounds of sanctions, Iran has shown that it doesn't mind being an international pariah.

Still, the administration has few options. If this latest round doesn't work, the choices will grow narrower — go to war or learn to live with a nuclear Iran.

The problem is at the heart of one of the administration's highest foreign policy priorities: halting the spread of nuclear weapons. American officials believe that if Iran goes nuclear, other nations in the greater Middle East will feel compelled to follow suit, including Turkey, Egypt and possibly Saudi Arabia.

Iran insists its network of nuclear reactors and enrichment facilities is meant only to produce energy and medical material for civilian use. But it has defied repeated demands by the U.N. Security Council to halt the enrichment of uranium.

Last year Iran announced plans to greatly expand its enrichment capability. And in February it began enriching its uranium to a higher level, an important step toward eventually producing bomb-grade material.

The draft U.N. sanctions resolution that the U.S., Russia and China introduced Tuesday goes further than earlier sets of penalties against Iran, with stiffer measures meant to curtail its military, financial and shipping activities. It would freeze assets of nuclear-related companies linked to the Revolutionary Guard, and it calls on member nations not to provide fuel or port services to ships carrying banned cargo to the Islamic republic.

The U.N. sanctions, also backed by France, Britain and Germany — are meant to lay a foundation for adoption of complementary and likely tougher penalties by Congress and the European Union.

But Iran has a history of deftly adapting to outside pressure.

"Sanctions by themselves will not do the trick," said Alireza Nader, an Iran specialist at the RAND Corp. think tank. He believes Iran's ruling clerics view their pursuit of a nuclear weapon as a matter of survival.

"I don't think anybody thinks these particular sanctions are going to trigger Iran to give up its nuclear program," said Sharon Squassoni, a nuclear proliferation expert at the Center for Strategic and International Studies.

But sanctions can make life more difficult — technically, financially and politically — for Iran.

"These sanctions are making it costlier, so that goes into the calculations that Iranians are making" about the future of their program, Squassoni said.

The initial set of U.N. sanctions against Iran was based on a Security Council resolution passed in December 2006.

It called for member nations to take "necessary measures" to prevent the supply, sale or transfer — by land, sea or air — of all materials, equipment, goods and technology which could contribute to Iran's nuclear activities.

Subsequent U.N. resolutions in March 2007 and March 2008 made similar requests, while repeating demands that Iran come clean on its nuclear program.

Despite this, Iran has made substantial advances in its nuclear program, parts of which are still shrouded in secrecy.

U.S. officials say it remains unclear whether the top Iranian leadership has made a decision on whether to actually build a bomb. But they add that they are still on a path to be able to do so someday.

Gen. James Cartwright, the vice chairman of the Joint Chiefs of Staff, told Congress last month that if and when Iran decides to build its first bomb, it could amass enough highly enriched uranium to do so in as little as 12 months.

Tuesday's proposed new U.N. sanctions resolution is markedly tougher than its predecessors, although the penalties could be watered down during deliberations by the 15-member Security Council.

The sanctions would target individuals and institutions with links to Iran's nuclear program, including the Revolutionary Guard, which controls companies, as well as organizations tied to weapons proliferation.

Both organizations and individuals would be added to a list of those subject to an asset freeze and travel ban that is still being compiled.

The March 2008 resolution had authorized inspection of cargo suspected of containing banned items on planes and ships owned or operated by Iran Air Cargo and the Islamic Republic of Iran Shipping Line.

The new proposal would call on U.N. member nations to ban the supply of fuel or services to Iranian owned or contracted vessels suspected of carrying prohibited cargo. The vessels could be boarded and inspected only if the ship's flag state agrees.


EDITOR'S NOTE — Robert Burns has covered national security and military affairs for The Associated Press since 1990.