WASHINGTON -- It's a prospect so alarming that it was nearly unthinkable before this month's attacks on the World Trade Center and the Pentagon.
But does the al Qaeda terrorist network headed by Osama bin Laden have nuclear weapons?
Nobody who knows for sure is talking publicly. Yet for much of the last decade, government reports and intelligence experts have been warning that bin Laden has been trying to build the bomb.
The reports have been sporadic but persistent: A 1999 article in the Jerusalem Report magazine claims "bin Laden has several nuclear suitcases," and a 1998 New York Times article says that a bin Laden aide was arrested in Germany on charges of trying to buy highly enriched uranium.
When Time magazine asked bin Laden in late 1998 what his nuclear intentions were, he cagily replied: "Acquiring weapons for the defense of Muslims is a religious duty. If I have indeed acquired these weapons, then I thank God for enabling me to do so."
There's a big difference, of course, between purchasing the right material -- and building a bomb, maintaining it, and successfully delivering it to its intended target. Nuclear weapons also have relatively short shelf lives, meaning a supply of replacement fuel eventually would be required.
"It's difficult to know if he has (nuclear weapons)," said Kimberly McCloud, a researcher at the Monterey Institute of International Studies who tracks weapons of mass destruction. "We know he's been interested in it, and that's reason for concern. At the same time, we don't know if (he) has weaponized it."
One shortcut to membership in the nuclear club is a portable tactical device, often called a "suitcase nuke."
Both the U.S. and the former Soviet Union created such weapons with about 1 kiloton of explosive power -- the equivalent of 1,000 tons of TNT -- which is enough to level a small portion of a city. The American version was called the Special Atomic Demolition Munition, or Mk-54, and was designed to be carried by a single paratrooper, then detonated by timer.
"You're talking about a bomb, a device with a capability of 1 kiloton of destruction, which is a massive capability that would cause severe destruction of a major inner city area, perhaps causing a multitude of buildings to collapse with the people inside of them," Rep. Curt Weldon (R-Pennsylvania) said in 1999.
The Soviet military created similar devices -- and then, apparently, misplaced some during the turbulent dissolution of the Soviet Union a decade ago.
Alexie Yablokov, Boris Yeltsin's former science advisor, told a U.S. House committee in 1997 that he believed dozens of the "suitcase-size nuclear munitions" were missing. At the time, the U.S. State Department said it was satisfied with Russia's assurances.
Some analysts who follow the topic stress there's little hard evidence to suggest a nuke-capable al Qaeda.
"We have no evidence at all that bin Laden has access to nuclear weapons," said Anthony Cordesman, a senior fellow at the Center for Strategic and International Studies who specializes in the Middle East and Southeast Asia.
"He now has shown an interest," Cordesman said. "George Tenet has made public remarks on this. No one has see that there is a clean chain of evidence that he has the capability. But no one can account for the Russian nuclear weapons."
Cordesman referred to speeches by CIA Director George Tenet, including a briefing that he gave in February. At the time, Tenet said: "The missile and (weapons of mass destruction) proliferation problem continues to change in ways that make it harder to monitor and control, increasing the risk of substantial surprise."
Perhaps the most detailed glimpse of bin Laden's capabilities comes from the testimony of Jamal Ahmad al-Fadl, a native of Sudan and ex-bin Laden associate who testified for the U.S. government in the World Trade Center bombing trial earlier this year. Al-Fadl testified he spent years trying to obtain highly enriched uranium for bin Laden.
The U.S. government seems to agree. Kenneth Karas, a federal prosecutor in that case, urged the jury in May to remember "the efforts by al Qaeda to obtain components of nuclear weapons and remember bin Laden's endorsement of what he called the Islamic nuclear bomb."
About the only thing that's certain is that if al Qaeda and bin Laden have the materials, making a nuclear weapon may not be that difficult.
A report by Carey Sublette, distributed by the Federation of American Scientists, recalls a 1960s experiment conducted by the U.S. government. In it, three newly graduated physics students were asked to develop a nuclear weapon using only publicly available information.
The result: "They did develop a viable design after expending only three man-years of effort over two and a half calendar years. In the years since, much more information has entered the public domain so that the level of effort required has obviously dropped further."
