VIENNA, Austria — Both regimes are suspected of running covert nuclear-weapons programs. Both are increasingly defiant, accusing Western envoys of meddling in what they insist is their right to develop peaceful nuclear technology.

By refusing to blink or budge, Iran and North Korea have the international community scrambling to cool and contain two high-stakes cases of nuclear brinksmanship — one in the Middle East, the other on the Korean peninsula.

"Clearly, these issues are reaching critical stages at the same time," said Terence Taylor, an expert on weapons of mass destruction who runs the Washington office of the International Institute for Strategic Studies. "You're seeing the limits of treaties and diplomatic activities."

Despite the similarities between the two cases, the West is approaching them differently — asking Iran to merely limit its nuclear activities in exchange for economic incentives, while insisting that North Korea drop even its civilian nuclear-power program.

"The two cases are different, and therefore the approaches are different," State Department spokesman Adam Ereli said yesterday. "The substance of the programs, the substance of the policies are not the same, and therefore you're not going to deal with them the same way."

The Vienna-based International Atomic Energy Agency (IAEA) holds an emergency meeting of its 35-nation board of governors today to review the standoff with Iran, which announced yesterday it had resumed uranium conversion at one of its nuclear facilities.

The IAEA could refer Iran to the U.N. Security Council, which has the authority to impose economic and political sanctions.

Developing countries on the IAEA board, led by South Africa, Brazil and Argentina, fear the attempt to force Iran to give up sensitive nuclear activities could one day be used against their own nuclear programs — and therefore object to it.

Iran insists its nuclear program is peaceful and geared solely toward generating electricity. But the United States and others contend it's hiding a weapons program.

With its vast petroleum reserves, Iran has a credibility problem. Why, many wonder, does it need nuclear energy when, by some estimates, its natural-gas reserves won't run dry for 200 years?

"There is no logic behind a peaceful nuclear program in Iran," said Alireza Assar, an Iranian scientist living in exile in Austria.

"Axis of evil"

President Bush once called Iran, Iraq and North Korea an "axis of evil." Ever since the U.S.-led invasion of Iraq, Iran has been concerned it might be next for military action.

North Korea's motivations are clearer — its army faces hundreds of thousands of South Korean and U.S. troops across the border, and for years North Korea's leaders were convinced they faced the threat of an American invasion.

Up to now, diplomats have resorted to a combination of threats and enticements in an effort to get both nations to abandon their nuclear ambitions. Neither has achieved a breakthrough, though envoys involved in talks with North Korea remain hopeful that the country's desperate economic and energy needs will be the lever the West is looking for.

Britain, France and Germany, negotiating for the European Union (EU), offered Iran a package of economic, political and technological incentives in return for assurances that it would not pursue nuclear weapons. On Saturday, Iran rejected the package.

"It's now clear that the best course of action is to refer the case directly to the U.N. Security Council," said Farid Soleimani of the Paris-based National Council of Resistance of Iran, an exiled opposition group.

The IAEA board is expected to issue at least a stern warning to Iran, and the EU and the U.S. are likely to press for Security Council involvement.

But getting agreement on sanctions from key Security Council members — including Russia, which has an $800 million contract to build a reactor in the Iranian port of Bushehr — could be tricky.

No warheads yet

For now, the international community is playing for time and hedging its bets on expert assessments that suggest Iran is a long way from building a warhead.

"Even the most concerned and skeptical of intelligence agencies now estimate that Iran is nearly a decade away from developing a nuclear weapon," said Daryl Kimball, executive director of the Washington-based Arms Control Association.

North Korea, by contrast, is widely considered far more advanced in its nuclear program. North Korea claimed in February that it already had atomic weapons.

On Sunday, deadlocked disarmament talks aimed at persuading the North to renounce nuclear weaponry were recessed for three weeks. U.S. officials said the negotiations stalled over the North's demand that it be given a nuclear reactor — a notion rejected by all six countries involved in the talks.

The IAEA's ability to intervene in North Korea is limited because North Korea, unlike Iran, has withdrawn from the Nuclear Nonproliferation Treaty.

"There's a lot at stake there," weapons expert Taylor said. "North Korea is not just an issue of nuclear capabilities. They also have a very large conventional [weapons] capability. That raises questions about what they could do if it came down to the use of force."

But Taylor sees some chilling similarities between the two regimes.

"They are both very serious threats. If they develop full nuclear capabilities, they would represent a threat not only to countries in their own region but to the world," he said.