Updated: 9/1/10 - Both the U.S and Dutch authorities have cleared the passengers of any criminal wrongdoings.
Two Men on a United Airlines flight from Chicago were detained today when the plane arrived in the Netherlands.
U.S. officials say luggage belonging to one of the men contained what appeared to be mock bombs - and they may have been testing the security system.
CBS News Justice correspondent Bob Orr reports U.S. officials are still trying to figure out whether or not this is a real threat. But, it is suspicious. Two men who flew from Chicago to Amsterdam have now been arrested the Netherlands.