Paris -- When North Korea announced its nuclear test last week, it was the latest sign that the effort to contain the spread of atomic weapons is breaking down: Several countries are on the verge of new uranium enrichment programs, and others have launched such efforts, say policymakers and experts.

Brazil recently restarted its uranium enrichment program, and Argentina and South Africa are interested in doing so.

Australia, which has large supplies of natural uranium, is considering launching an enrichment program.

Iran has defied requests by the international community to suspend its program to enrich uranium, the first step toward making fissile material for a bomb.

And North Korea"s defiant announcement of a test follows ones by India and Pakistan in 1998.

The rise of this "new generation" of nuclear states has sparked concerns that others could follow, and fueled fears that the more countries attain nuclear capability, the greater the risk that fissile material will fall into terrorist hands.

"We are at present at the unraveling of the nonproliferation regime and the global nuclear order that we"ve taken for granted," said Graham Allison, a former assistant secretary of defense under President Clinton, who now directs the Belfer Center for Science and International Affairs at Harvard University.

"This is a huge event whose importance may only become evident in five years ... In terms of global order, global nuclear order, this is a nuclear blast."

On Saturday, the U.N. Security Council unanimously adopted a resolution imposing sanctions on North Korea for its declared nuclear test five days earlier. But China"s reluctance to take part in inspections of North Korean cargo to stop the flow of weapons materials throws into doubt how effective the sanctions will be.

Policymakers point to three levels of problems with the Nuclear Nonproliferation Treaty, which has been in force for 36 years.

Under the treaty, countries that had nuclear weapons when the treaty went into effect -- the United States, Russia, Britain, France and China -- were allowed to keep them, while others were asked to forswear them, creating a system of "haves" and "have-nots."

The "haves" made the commitment to reduce and eventually eliminate their arsenals, while the "have-nots" agreed not to seek them as long as they could have nuclear technology for peaceful purposes.

Although the U.N. nuclear watchdog, the International Atomic Energy Agency, was charged with ensuring that those countries refrained from taking steps toward making fissile material, the treaty in effect permitted any country that wanted nuclear weapons capability go down that road.

Once a country masters uranium enrichment, it is relatively easy to go from low-level enrichment, which produces fuel for nuclear power plants, to high-level enrichment, which produces the material for a bomb.

Although 187 countries have signed the treaty, some developing countries are skeptical of the intentions of the five original nuclear states and reluctant to give up the option of some day enriching uranium, leaving the door cracked to nuclear weapons.

Immediately after the Cold War, the United States and Russia reduced their arsenals by thousands of nuclear weapons, but since then there has been a standstill. There are now about 27,000 nuclear warheads worldwide -- the majority in the U.S. and RussiaMost of the five recently have moved either to modernize or, in China"s case, expand their arsenal.

In the meantime, states that have pursued nuclear capability either outside the treaty or by hiding their programs have gone unpunished over the long term.

Three countries -- India, Pakistan and Israel -- refused to sign the treaty. Pakistan and India have developed nuclear weapons, and Israel is believed to have them. All three enjoy the favor and respect of the giants in the world community, setting an example of what countries can get when they have nuclear weapons.

India and Pakistan, which were sanctioned for undertaking nuclear tests, have seen those sanctions diminish, and India has been offered a multibillion-dollar deal with the United States that includes nuclear technology. The deal has yet to be approved by the U.S. Senate.

Two other countries have refused to abide by the treaty, although they signed it: Iran and North Korea, and the latter withdrew three years ago. Neither has suffered significant consequences for refusing to comply.

That is because until Saturday, the five veto-wielding members of the Security Council could not agree on a punishment for either country.

Finally, the only early warning system that a country might be going down the nuclear weapons road appears unable to do its job.

ADVERTISEMENT
The IAEA has failed to detect cheating by countries at an early stage because it lacks the authority for investigations. It also lacks enforcement power to stop what it does find and must report countries to the Security Council, which has had trouble agreeing on an appropriate punishments.

Western countries with nuclear arsenals want to work with the existing system, which allows them to keep their nuclear weapons. Their policymakers insist that overall the system is working pretty well. They note that under the NPT, several countries have given up their nuclear weapons, including the former Soviet republic of Kazakhstan, Libya and South Africa.

A senior U.S. official involved in nuclear policy noted that, "There are about three dozen countries that have the intellectual, technological capabilities to have and develop a nuclear weapons capability but have chosen not to. Those, such as Japan and Germany, it wouldn"t take them long to make that transition, but they haven"t and the NPT is part of the reason."

But developing countries say they have no wish to give up their right to uranium enrichment and do not trust the United States or other nuclear countries to be consistent suppliers of the nuclear material they would need to run power plants. Furthermore, they say there is no guarantee that one of the nuclear counties won"t attack them.

Daniel Pinkston, a nuclear security expert at the Monterey Institute in California, emphasizes that the states that have pursued nuclear weapons either secretly or by refusing to sign the NPT are all countries in tense neighborhoods -- the Middle East or Asia -- where they feel they could easily be attacked.

"Nuclear weapons can be attractive for the security benefits, and those might outweigh the benefits from participating in the nonproliferation regime ...," he said. "So unless you can resolve the security dilemma, you aren"t going to resolve the problem."

The United States has helped to prevent some of its non-nuclear allies from going the nuclear weapons route by guaranteeing their security.

For instance, in Japan, although a political faction would like to develop weapons, policymakers are willing to rely on the U.S. to protect it, saving Japan the money and manpower to use on other needs. Taiwan and South Korea fall into that category as well.

The problem is that once one country in an area obtains nuclear weapons, others might get nervous and the situation becomes hard to control.

Most worrisome to some of the nuclear states and their allies is that the IAEA has proved incapable of detecting transgressions by member states at an early stage.

Although Libya and South Africa gave up their nuclear weapons programs, the IAEA was not aware of the Libyan program until the day Moammar Gadhafi announced they were giving it up.

And Iran had a program for 18 years that went undetected by the IAEA until it was disclosed by an anti-government group.

*Times staff writers Douglas Frantz in Los Angeles and Bruce Wallace in Tokyo contributed to this report.