Dutch police have questioned two men who arrived at Amsterdam airport from Chicago, after US authorities spotted "suspicious items" in their luggage.
One checked-in bag reportedly contained a mobile phone strapped to a medicine bottle, as well as knives and watches.
However, a spokeswoman for the US Department of Homeland Security said none of the items were dangerous "in and of themselves".
But the information was passed to the Dutch authorities, who held the men.
It is likely that they will appear in court later before a judge, who will decide whether they should be released or remanded into custody pending possible charges of preparing a terrorist attack, says the BBC's Geraldine Coughlan in the Netherlands. BBC News
