A passenger toted a 20-pound stash of radioactive thorium powder onto a bus in his luggage. Another smuggler, unwisely, stuck a highly radioactive capsule in his trousers pocket as he boarded a flight. Chechen rebels were the apparent customers for stolen radium in a third case.
The new nations of Central Asia have become a traffickers' marketplace for radioactive materials. It was the place Jose Padilla headed to, Pakistani investigators say, when the al-Qaida suspect sought the stuff of a "dirty bomb."
Confronting the threat is a big job, but the U.S. government has begun sending detection equipment to border posts in the vast region and training customs officers in intercepting nuclear contraband.
Pakistani officials said Padilla, now in U.S. custody, traveled to a Central Asian country in April hoping to buy radioactive materials. The American convert to Islam had conferred with senior members of Osama bin Laden's al-Qaida network about detonating a radiation weapon, or "dirty bomb," in the United States, U.S. authorities say.
Such a device would not be a nuclear bomb, with its devastating fission explosion, but instead would set off conventional explosives to scatter harmful radioactive material, contaminating and panicking people and forcing abandonment of parts of cities.
The Pakistani officials would not say whether Padilla was successful in obtaining radioactive substances, nor would they identify the country he was said to have visited.
Since the breakup of the Soviet Union in 1991, the newly independent Central Asian states -- Kazakhstan, Turkmenistan, Uzbekistan, Tajikistan, Kyrgyzstan -- have dealt with a legacy of abandoned nuclear materials and of facilities left poorly staffed after Russian specialists went home.
The only nuclear weapons in the region, in Kazakhstan, were withdrawn to Russia in the early 1990s. In 1994, a half-ton of highly enriched uranium -- raw material of nuclear bombs -- was spirited out of Kazakhstan in a U.S. operation.
But material for possible "dirty bombs" remains scattered and often poorly controlled in the region -- the cesium, strontium, cobalt and other radioactive substances used in medicine and industry, the low-grade uranium and radioactive waste of nuclear power plants.
"Protecting against radioactive sources is much harder than securing nuclear materials," said Dmitry Kovchegin, a nuclear proliferation specialist at Moscow's Center for Policy Studies in Russia. "It's not so hard to create a dirty bomb, and it's not so hard to find the material. It's used everywhere."
Some cases from the marketplace where Padilla allegedly shopped, based on local media reports:
--In March, a radiation check of a bus crossing into Russia from Kazakhstan found a Russian passenger had packed at least 10 kilograms (22 pounds) of thorium-232 powder into his luggage. Its radiation was "hundreds of times" normal background levels, authorities said. Its origin and destination were not reported.
--In Kyrgyzstan, airport guards grew suspicious of a man who looked ill as he boarded a flight to the United Arab Emirates. The Uzbek was found to have pocketed a smuggled capsule of what he was told was plutonium. Local media said it emitted fatal doses of radiation at close range. No subsequent reports emerged about the 1999 case.
--In July 2000, two brothers from Kazakhstan were arrested after allegedly smuggling radium-226 into Russia to sell to Chechens. Chechen separatists in the mid-1990s had threatened to detonate "dirty bombs" in Moscow, but never did.
--In Tajikistan, six residents were convicted in April 2000 in the theft from a uranium processing plant of 1.5 kilograms (3 pounds) of uranium mixed with highly radioactive cesium-137. It was not reported how enriched -- suitable for nuclear weapons -- the uranium was.
All of those substances theoretically could be used for a radiation dispersal bomb.
Reports indicate that Pakistan and Afghanistan, until eight months ago a hub for international terrorism, were the destination in some nuclear trafficking cases in recent years. Those monitoring the situation have no way to judge how many other such operations succeeded in smuggling radioactive substances.
The U.S. Customs Service last year conducted a three-week course in Texas for 80 border officers from the five Central Asian republics, focusing on radioactive contraband. The Americans also have dispatched detection equipment to the Russian-Kazkh border and Uzbekistan.
Last month, Washington and Moscow announced formation of a joint task force to study securing radioactive sources in Russia. This "shows how serious this issue is and that we're ready to solve it," said the Russian atomic energy minister, Alexander Rumyantsev. No similar comprehensive approach has been organized yet for Central Asia.