Dutch authorities have detained two Yemeni men at Amsterdam's Schiphol airport on suspicion of a terrorist conspiracy, after a tip-off from the United States.
The US Department of Homeland Security alerted Dutch authorities to suspicious items found in the men's luggage before a domestic American flight from Alabama to Chicago.
They included knives, watches and a mobile phone taped to a plastic medicine bottle.
Officials say there was no indication of explosives, so the luggage was cleared.
The two men checked in at Chicago for a flight to Yemen but took a direct flight to Amsterdam instead, leaving their luggage behind.
Under Dutch law, the men can be held without charge for up to six days.