Updated 10:11 a.m. ET
Two men arrested in Amsterdam may have been conducting a dry run for a potential terrorist attack, U.S. officials said Tuesday after a cell phone taped to a bottle of medicine and a knife and box cutters were found in one of the men's luggage.
U.S. investigators are pursuing leads in three American cities, according to officials speaking on condition of anonymity to discuss the investigation.
The arrests come at a time of heightened alert just days before the ninth anniversary of the Sept. 11, 2001 terror attacks in the U.S.
On Sunday, authorities found the suspicious items - a cell phone taped to a medicine bottle, multiple cell phones and watches taped together, and a knife and box cutter - in one of the men's checked luggage. The man and his luggage were headed to separate international destinations, which also raised concerns.
None of the items found on the men or in their luggage violated U.S. security rules. But the items and the men's changing travel itinerary may have been a deliberate test of the U.S. aviation security system to determine what would raise red flags.
Neither man was on any U.S. terror watch lists, White House spokesman Robert Gibbs told CNN television Tuesday.
A U.S. law enforcement official identified the men as Ahmed Mohamed Nasser al-Soofi and Hezam al-Murisi. Al-Soofi is of Yemeni descent, one of the law enforcement officials said.
The pair were arrested Monday Amsterdam's Schiphol Airport after getting off a United Airlines flight from Chicago.
RTL Television News broadcast video footage filmed on a passenger's cell phone of armed law enforcement officers escorting two men off the plane, their hands bound behind their backs. The officers' weapons were holstered and there appeared to be no resistance.
They were being held at the airport for questioning, but neither has been charged with any offense in the Netherlands, said Martijn Boelhouwer, spokesman for the national prosecutor's office. Under Dutch law, the men can be held without charges for up to six days. No charges have been filed against the men in the U.S., a law enforcement official said.
Al-Soofi was questioned as he went through security in Birmingham, Alabama, on his way to Chicago, one of the officials said. He told the Transportation Security Administration authorities he was carrying a lot of cash. Screeners found $7,000 on him, but he was not breaking any law by carrying that much money.
Al-Soofi was supposed to fly from Chicago to Washington Dulles International Airport in Virginia and then on to Dubai, one of the officials said. But when he got to Chicago, he changed his travel plans to take a direct flight to Amsterdam, while his luggage went on to Virginia.
On international flights, passengers and their luggage must be headed toward the same destination, according to U.S. policy.
Al-Murisi also changed his travel plans in Chicago to take a direct flight to Amsterdam, raising suspicion among U.S. officials. Federal Air marshals were on the flight from Chicago to Amsterdam, a law enforcement official said.
Inside the luggage, TSA screeners found seven cell phones, one of them taped to a Pepto-Bismol bottle and three others bound together. Screeners also found several watches wrapped in tape, along with a box cutter and three large knives, reports CBS News chief justice correspondent Bob Orr.
Homeland Security spokeswoman Amy Kudwa said once officials found the suspicious items, they notified the Dutch authorities.
Alabama's director of homeland security, Jim Walker, said al-Soofi had been living in Tuscaloosa, Alabama, and working at a convenience store for about the last three months. He said there was nothing that al Soofi had done in Alabama that brought him to the attention of Alabama officials.
Security at Amsterdam's main airport has been boosted this year, after Umar Farouk Abdulmutallab, a Nigerian student, flew from Schiphol airport to Detroit on Christmas Day with explosives in his underwear. Abdulmutallab allegedly tried to detonate the explosives over the United States before being grabbed by passengers and crew.
After the Abdulmutallab security lapse, Schiphol ordered 60 new full body scanners to screen passengers flying to the United States. Those who do not pass through the scanners are patted down.
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