FORMER SEMIPALATINSK NUCLEAR TEST SITE, Kazakhstan – Arcania does not exist on any map, but nuclear inspectors believe it could help save the world from catastrophe.

The imaginary country they have set in the vast steppes of Central Asia is the site of an ongoing monthlong exercise that organizers say could provide essential groundwork for a global alarm system for detecting nuclear explosions.

The initiative has its roots in the Comprehensive Nuclear Test Ban Treaty, which was signed by 35 of the 44 states that participated in a 1996 disarmament conference and that, at the time, possessed nuclear power or research reactors.

The treaty cannot come into effect until all participants sign. And some of the holdouts – including the United States, China, North Korea, Iran, India and Pakistan – have balked, in part because they fear that the ban cannot be properly enforced.

The current game is meant to prove the Comprehensive Nuclear Test Ban Treaty Organization, CTBTO, can verify and enforce the terms of the treaty.

This onsite verification system is the final link in a chain that will rely – for initial test detection – on a global network of 321 monitoring stations able to sense seismic tremors, sound waves and radioactivity from thousands of miles away.

According to the script of the exercise, alarm bells were set off in late August when seismic stations registered a tremor in northeast Arcania – a renegade nation with civilian nuclear capabilities and a recorded history of underground testing.

Distressed that its neighbor was scheming to create a nuclear arsenal, equally fictitious Fiducia asked the CTBTO to conduct an immediate onsite inspection. Arcania, which reluctantly ratified the treaty in 2003, expressed surprise but granted entry to the inspection team.

The organization chose this site because of its remoteness and its melancholy history as the Soviet Union's main nuclear weapons testing range. Between 1949 and 1989, Soviet authorities detonated more than 450 atomic weapons here, leaving behind a disastrous legacy of health problems and environmental ruin.

With the nearest town of Kurchatov around 90 miles away, hauling more than 50 tons of tents, computers and high-tech laboratory equipment in steel cargo containers to base camp has posed a big logistical challenge.

“For real you could be in the middle of nowhere and you want to see the logistical problems of operating in the field and how that impacts on your ability to work effectively,” said John Walker, a British diplomat with more than two decades experience in arms control.

The exercise, which has brought together more than 40 scientists and diplomats from over a dozen countries, has been executed with a fastidious adherence to real-life constraints.

One recent day, scientists clad in disposable safety suits returned from six-hour shifts after examining suspect sites. They were rigorously showered with cold water before being allowed into the inspectors' area.

Tents in the inspectors' quarters were a hive of activity with analysts deciphering streams of technical data with a bewildering array of computer and laboratory equipment.

On a lighter note, the Arcanian team was thorough in giving its nation a full-fledged identity, including a national anthem to the tune of socialist anthem, the Red Flag.

Participants said one of the exercise's aims was to test how well the inspection regime would work under real-life conditions. They encountered them: No one appeared to have properly anticipated the cold and wet weather that battered the camp in the opening days.

“You should have been in the field a few days ago, when a tornado came through and the temperature dropped to 5 degrees Celsius (41 Fahrenheit),” Kayrat Kadyrzhanov, director general of Kazakhstan's National Nuclear Center, told reporters at a briefing.

“Of course, our guys are pretty tough, but some of the foreigners wanted to just quit and leave.”

American resistance has been a critical obstacle to the treaty.

“The biggest problem there has been over the past eight years is that (U.S. President George W.) Bush's administration has been dead set against the CTBTO,” said Rebecca Johnson, executive director of the London-based Acronym Institute for Disarmament Policy.

That could change soon, with both U.S. presidential contenders signaling they would reconsider the pact.

In part, the Kazakhstan exercises were intended to reassure holdouts of the CTBTO's ability to detect nuclear tests.

“India and Pakistan, not to speak of North Korea, rightly wonder why they should sign up to the treaty if they believe they can be hoodwinked anyhow,” said Nadezhda Belyashova, head of the Kazakhstan's Geophysical Research Institute and adviser to the CTBTO.

Participants said the treaty is essential to the future of non-proliferation.

“If we don't get the treaty, I can guarantee you that the nonproliferation regime will not have long to last,” said Johnson of the Acronym Institute.

And nuclear arms in the hands of unstable governments will lead inevitably to “a heightened risk of accidental use that could be catastrophic.”