VIENNA, Austria - Veiled Iranian threats to quit the Nonproliferation Treaty conjure up the case of North Korea, which announced it had atomic weapons shortly after walking away from the treaty.

But while the North escaped punishment by the U.N. Security Council, any move by Iran to break out of the pact will likely bring a tougher response.

For the second time in three days, Tehran warned Monday that it could rethink its adherence to the pact, meant to stop the spread of nuclear weapons, if the treaty"s provisions are used against the country.

At issue is uranium enrichment, which can make both nuclear fuel or the fissile core of warheads, and an activity that Iran insists it has a right to under the NPT, which expressly permits countries to develop peaceful nuclear programs.

Iran insists its intentions are purely peaceful, but growing international concern about its aims contributed to Tehran being reported to the Security Council by the International Atomic Energy Agency"s 35-nation board.

Reiterating President Mahmoud Ahmadijead"s indirect threat, his spokesman, Gholamhossein Elham, warned Monday that Tehran will "revise" its policy toward the treaty signed by Iran and 90 other nations if it is used against the country.

He said the world must recognize Iran"s rights under the treaty an allusion to the provision of the pact that recognizes countries" rights to peaceful nuclear programs and indirectly nuclear enrichment for nonmilitary purposes.

"Otherwise," he said, "there is no reason to continue our current nuclear policy while we are deprived of the positive aspects of the treaty."

Only one other country North Korea has withdrawn from the treaty since it came into force 36 years ago, and the Tehran leadership may be hoping the Security Council"s meek response to that decision could be repeated in its own case.

While the Security Council expressed concern about North Korea"s nuclear program, it undertook no concrete steps to punish the country. U.S. calls for economic or political sanctions foundered on Chinese and Russian opposition.

Iran may also be counting on backing from Moscow and Beijing, both veto-carrying Security Council members. While they share international worries about Tehran"s nuclear ambitions, they forced the other permanent council members the United States, Britain and France to agree to no action at the Security Council at least until March, when the council considers a new report on Iran"s nuclear program from IAEA head Mohamed ElBaradei.

Still Iran is not North Korea and 2003 not 2006.

Back then, increasing concerns about Iraq including the growing threat of U.S. invasion deflected some of the focus on North Korea. And because Pyongyang already was a pariah state with only a subsistence economy, it had little to lose from U.N. political and economic sanctions.

With China the North"s main lifeline to the outside world, Beijing was given a leading role in engaging it outside the U.N. system along with other countries key to solving the conflict the United States, Russia, South Korea and Japan. The on-off six-party talks meant to convince North Korea to disarm in exchange for economic and political incentives were born in August 2003.

But that approach is unlikely to work for Iran, leaving the prospects of harsh U.N. Security Council action much more likely should it quit the nonproliferation treaty.

Attempts outside the U.N. framework to persuade Iran to ease concerns about its nuclear ambitions have failed. Britain, France and Germany, negotiating for the European Union, threw in the towel last month after Iran announced it planned to resume small-scale enrichment.

And on Monday, Iran indefinitely postponed new talks with Moscow on reducing fears it would misuse enrichment by moving its program to Russia just two days before they were to happen.

"The Europeans were willing to offer carrots and Iran has turned that down, so the logical thing is to step up pressure on Iran within the Security Council" should it quit the Nonproliferation Treaty, said former Iraq nuclear inspector David Albright.

For isolated North Korea, China is crucial for oil and other basics. Not so for Iran, which remains interconnected with the world and would therefore be squeezed by Security Council sanctions.

Ironically, Iran, OPEC"s second-largest oil exporter, depends on Europe and India for 40 percent of its gasoline because of a lack of refinery capacity, said Albright, now head of the Washington based Institute for Science and International Security.

Albright says that with Russia and China increasingly sharing concerns about Iran"s nuclear aims, even those erstwhile allies would be hard put to veto firm Security Council action if Iran leaves the NPT.

"It may tip them into the camp," he said.

At the least, said Albright, such an Iranian defection would force Russia to end all nuclear cooperation with Iran and effectively mothball operation of its nearly completed billion-dollar Bushehr nuclear reactor.

Moscow, which built Bushehr, will have no choice but to cancel arrangements to provide it with nuclear fuel and Iran will not have enough enriched uranium to fire it up for at least 10 years, he said.