KABUL, Afghanistan - Materials left behind in a compound used by Osama bin Laden's al-Qaida network - including a booklet offering advice on how to survive a nuclear explosion - suggest the terrorist group may have been trying to develop chemical arms and other unconventional weapons.
Foul-smelling liquids and charred papers covered with chemical formulas littered a makeshift laboratory in one al-Qaida building in the heart of Kabul. Maps, mines and computer manuals were found in others.
Homeland Security Director Tom Ridge said yesterday that the documents are consistent with bin Laden's statements saying he desired nuclear weaponry.
But papers found detailing how to make a nuclear device were ``taken off the Internet some years ago" and could have been widely available to people other than the al-Qaida terrorists, he said.
U.S. officials have said that they had no information to suggest bin Laden has succeeded in gaining nuclear weapons.
But ``we have to be prepared for all eventualities including a nuclear threat," Ridge said.
The Kabul compound appeared to have taken a direct hit from what northern alliance soldiers said was a U.S. rocket.
The Times of London newspaper reported Thursday that designs for nuclear weapons, bombs and missiles - written in Arabic, German, Urdu and English - were among the debris left behind.
``There are descriptions of how the detonation of TNT compresses plutonium into a critical mass, sparking a chain reaction, and ultimately a thermonuclear reaction," The Times said.
Room after room was filled with papers, formulas and maps, some partially burned, some with handwritten Arabic notations. There was a yellowed page from an old issue of Plane and Pilot magazine - a story titled ``A Flight to Remember."
At the rear of the main house, one room contained mountains of papers, some from training manuals showing diagrams of weapons. An English-language book described how to use a recoilless rifle. Small, anti-personnel mines littered the floor of another room.
An alliance soldier in camouflage dress, Mohammed Nisar, walked through three houses pointing out pieces of paper with formulas, handwritten diagrams, pictures of rockets and other weaponry. In the basement of one house was what looked to be a laboratory.
In another house where the al-Qaida men resided, according to Nisar, four different types of land mines were found. Northern alliance troops had emptied two old railway cars parked in the yard that its soldiers said had been packed with arms and ammunition.
``Look, you can see the land mines," Nisar said, moving to pick one up. ``It's safe now; we have disarmed it."
Deep beneath the house were what seemed to be bunkers, with a roof of fresh cement. In one were parts of weapons, with the barrels of anti-aircraft weapons propped up in the corner.
In the yard and in the rooms were more papers and diagrams - some in Arabic, some in Persian, some in Urdu - and maps with large circles to mark locations.
Earlier this year, The Associated Press acquired an 11-volume Encyclopedia of Holy War, written in Arabic and dedicated to bin Laden and the Taliban.
Another sprawling al-Qaida compound, built on a former Scud missile base in the hills that surround Kabul's Darulaman Palace, apparently served as training grounds.
``We found lots of books and papers and newspapers," said Haji Abdullah, a northern alliance commander. ``We threw most of them out."
A laminated certificate retrieved from the rubble identified the holder as a ``military training instructor," alliance soldier Jan Aga said.
The northern alliance, which now controls the abandoned base, had one Pakistani in custody, Naimad Ullah. Just 17, Ullah could only speak Urdu. He looked terrified.
``I am afraid to say anything, they will take my head off," he said in Urdu. The northern alliance soldiers said they had kept him safe for three days and had captured him on the front lines north of Kabul.
Ullah said he was a student at a madrassa, or religious school, in Pakistan and had come to fight with the Taliban during his school holidays. His captors promised to keep him safe.
A letter left behind by another Pakistani was addressed to a brother in Peshawar,
Pakistan. Twelve days into the air campaign, Mohammed Khaliq had written: ``Don't worry about me. Pray for me five times a day. Our enemy is not strong; we will win. If we die here, there is no greater reward."
