Turkish authorities report they have detected more than 100 cases of such attempted smuggling in the last few years.
ABCNEWS was doing what some law enforcement officials say al Qaeda terrorists have known how to do for years.
"For a decade, they've sought nuclear weapons," said Allison."[Osama] bin Laden has said it is his and al Qaeda's religious duty … to acquire nuclear weapons."
Documents in Arabic seized from one of bin Laden's top aides five years ago show how he apparently planned to use shipping containers packed with sesame seeds as part of a plan to smuggle high-grade radioactive material to the United States.
Allison is concerned that what ABCNEWS did as a test may have already been done for real. "There's no reason to think that they haven't," he said.
Suitcase Labeled ‘Depleted Uranium’
Hours after the ABCNEWS team arrived in Istanbul, the suitcase of radioactive material was prepared for shipment by sea to the United States. The suitcase was placed inside an ornamental Turkish chest that was carefully marked as containing depleted uranium, in case inspectors discovered it.
Then, in the middle of a busy Istanbul street, the chest itself was crated and nailed shut. The crate containing the suitcase was then nestled alongside crates of huge vases and Turkish horse carts in a large metal shipping container that was ordered from a company that arranges shipments to the United States.
"If it were a real weapon, you know, that you'd managed to get out of the Soviet inventory, [it] would fit in this container," said Allison. "A battlefield nuclear weapon, an artillery shell would fit fine in there."
The company hired to handle the shipping did not know, nor did its workers check to see, what was inside the crate. The company told ABCNEWS this week that it is re-evaluating its practices in light of this report.
The container, with the suitcase inside, left Istanbul on July 10, bound for the Port of New York, where U.S. Customs Service officials have very publicly claimed they've made huge improvements to prevent anything radioactive from getting through.
"We're doing everything we possibly can to keep terrorists and terrorists weapons out of this country," said Customs Commissioner Robert Bonner.
At 2 a.m. on July 29, the ship carrying this suitcase cleared the Verrazano Bridge and entered New York Harbor. At this point, no one had asked a single a question about what was in the container.
A Dangerous Delivery Device
This scenario was too close for comfort for Allison, who explained that a weapon smuggled in this way could be armed in advance and ready to fire — and the ship could be the delivery device.
"The ship, I think, is one of the most dangerous delivery devices," said Allison. "A weapon or material in the belly of a ship has been one of the nightmare scenarios for people that think about how nuclear weapons might arrive in the U.S."
The ship carrying the container was tied up at the Staten Island dock in New York, where the Customs Service says it has a state-of-the-art system in place to detect even a small, low-level amount of radioactive material.
"We're doing whatever it takes to screen the high-risk containers," said customs inspector Kevin McCabe, the chief of the contraband enforcement team, who did not know about the test when he demonstrated the screening measures to ABCNEWS.