Scientists charged with international nuclear safeguards now assume that North Korea has a cache of weapons-grade plutonium slightly larger than a basketball, or enough for about nine bombs - since North Korea, for technical reasons, had to reprocess the plutonium or lose it.
Moreover, they say, any credible future deal with the regime run in absolute secrecy by leader Kim Jong Il will require a minimum of seven or eight months of nearly unlimited access to North Korea - to uranium mines, dismantled plants, research and development, active or retired scientists, all records, and any sites deemed relevant.
Such access would go far past anything Mr. Kim has ever allowed.
Next week is the second anniversary of a standoff between the international community and Kim's regime.
On Dec. 30, 2002, IAEA inspectors monitoring 8,000 spent fuel rods were kicked out of North Korea in a move regarded at the time as a breach of what had been regarded as an inviolable "red line."
The move followed an esca- lation between the US officials and North Korea over a second, secret uranium program the US said the North was conducting.
Six-party talks on Korea hosted by China have stalled for half a year. Kim is thought to have awaited the US elections; Washington is preoccupied with the Iraq war. Yet unlike Iraq, which has proved to have no weapons of mass destruction, the North has, if anything, developed its program with ardor, scientists say - a further challenge to the Non- Proliferation Treaty, global security, and the White House.
Scientists here assume Kim has up to nine bombs of fissile material not only because North Korean scientists are capable of reprocessing fuel rods - but because to the threat of rust.
As time elapsed, Kim had to choose whether to scrap his hard-earned nuclear stockpile or reprocess it, says a Vienna-based diplomat with close ties to the inner circle of Mohammed ElBaradei, head of the International Atomic Energy Agency.
"The rods were canned, welded, and placed under water for cooling [in the early 1990s]. But we know the welds were corroding, and plutonium reacts very badly to rust," says the diplomat. "DPRK [North Korea] would have had to reprocess for safety considerations, and that is what we assume."
The Vienna-based diplomat says that after December 2002, the IAEA was "blind."
"It can't see inside buildings, we don't have anyone on the ground," he comments. "We [need] six to eight months to restore a loss of continuity of information and knowledge. That means use of whatever technology is needed to verify, and unfettered access."
Such access would fall just short of the carte blanche that IAEA inspectors got in Iraq after the first Gulf War, but would be more than they have now secured through "additional protocols" granted for Iran. In Iran, inspectors have to give a few hours' notice. In North Korea, they will ask for snap inspections. Because it would go far past anything the North has so far allowed, many experts are skeptical Kim will agree to this.
While the IAEA has no direct evidence of an "enriched uranium" program, preliminary results from an IAEA investigation of the network of Abdul Khan, suggests the Pakistani scientist was a major supplier of aid and materials to North Korea, Libya, and Iran. While Libya seemed incapable of taking its program through the steps required to develop a uranium program, North Korea "needed little prompting," the diplomat says.
"You give someone the plans to assemble a complicated piece of furniture and they get home and make it halfway through. Then they have to call for help," the diplomat says. "That wasKhan's role. The Libyans constantly had trouble. We know Khan gave the North Koreans enough to get a good start, and we know they and the Iranians didn't need to call [Khan] as often. The Libyans finally couldn't run this stuff, but the DPRK has the people, trained in Moscow."
For example, the diplomat points out, the North Koreans took the design plans for an early-generation British plutonium Magnox reactor, built a 5-megawatt reactor, and were in the process of building 50- and 200-megawatt reactors. The Magnox had design flaws that the North worked out on its own.
Had the two larger reactors gone online as scheduled in 1995, they would have been capable of producing five to 10 bomb "cores" per year, according to the IAEA's website.
Last December, the IAEA sent a "nonpaper" to all participants in the six-party talks outlining "minimum requirements" for a genuine deal. It included access to whatever people, records, and sites they might deem necessary. IAEA officials want any such agreement backed by Security Council guarantees in case of violations.
Currently, IAEA officials are engineering the language used for North Korean access so it does not appear overly harsh. Words containing concepts like "unlimited," or phrases like "any place, anytime," are thought to echo language used in Iraq after Saddam Hussein was defeated in 1990. Because of that, a new rhetoric is employing such phrases as "full and final," "unfettered access, "complete and comprehensive."
"We need unfettered access, not to punish North Korea, but because there is no way to guarantee any safety otherwise," the diplomat notes. "At the same time, we don't want a US-run verification. If we get that, it will undermine our agency's credibility. We won't appear impartial."
Jon Wolfstahl, deputy director of the Nonproliferation Program at the Carnegie Endowment for International Peace, has been on the ground in North Korean facilities as part of an earlier US program for dismantling the program. He says it would take longer than seven to eight months of "unfettered" access to know the exact state of any weapons development.
"If it's just to find out what happened to the plutonium it would take longer than that," he says, noting earlier estimates that it would take two to three years just to answer questions about programs through the early 1990s.
Now that the US elections are over, it is still unclear how the Bush team will address North Korea. Mr. Wolfstahl feels the talks are fragmenting. Last June, the US appeared to back off from tough language requiring a "complete, verifiable, irreversible dismantling" (CVID) - but recent statements suggest the White House has readopted tougher language. Many Asia policymakers in Washington are deeply distrustful of a regime run on the basis of a cult of adulation for Kim, and whose diplomacy is legendary for its cleverness and dissimulations.
Both the US and Chinese team leaders of the talks, James Kelly and Wang Yi, also appear further removed from the process, with Mr. Kelly expected to retire from the State Department and Mr. Yi being assigned to Japan.
Some US experts and even IAEA officials caution against assuming too much about North Korea's capability. They say that in strict empirical terms, there is almost no evidence of bomb material. They describe a world that exists between circumstantial evidence, and hunches. "We can't actually say for certain we know that the North has any processed plutonium," said one Western nuclear expert in Vienna.
Paul Kerr, a specialist at the Arms Control Association in Washington, says that, "You could store it, but there are risks to that. There are safe ways to store it, but that appears to be beyond the capabilities of the North Koreans."
In the past, North Korea has built warehouses that appear from satellite imagery to be the exact proportions for a nuclear plant, and in the right location. But after North Koreans were paid millions of dollars to look inside, it was found to be empty.
Khan and his associates sold at least $100 million of equipment to Libya, including a nearly completed uranium enrichment facility, IAEA officials told the Los Angeles Times earlier this month.
IAEA officials and scientists say the North is pursuing its goals no matter the human cost.
Stories and eyewitness accounts of the North's brand of applied science have proliferated inside the IAEA in recent years, including those describing humans doing work that, in other states, only machines would do.
"I've talked to a Canadian eyewitness to the movement of nuclear material out of casks, who saw about a hundred men wearing lead aprons run into the plant and haul out rods one at a time. No other country would accept that, but the North Koreans will do what it takes to reach their goal," the diplomat says.
North Korea's program dates to the early 1980s, when Kim's father, Kim Il Sung, embarked on a nuclear path. By the late 1980s, the state had a reactor running.
The first Gulf war showed that Iraq was quickly developing a nuclear capability. The senior Kim invited IAEA inspectors in, hoping they would verify North Korea's declaration that it had no weapons-grade nuclear material.
Yet new technology and experience derived from Iraq allowed inspectors to find traces of weapons-grade plutonium. This sparked a crisis that led to an "Agreed Framework," administered by the IAEA, between the US and North Korea. But no other activity was monitored except the plutonium fuel rods and several other sites, and was regarded even at the time as incomplete.
"There are no plans for another rounds of talks," says Derek Mitchell, of the Center for Strategic and International Studies. "Right now, the ball is in North Korea's court.
• Howard LaFranchi contributed from Washington.