Policemen stand guard on a roof top in A [Getty Images]

Policemen stand guard on a roof top in Amsterdam before the memorial service of the Second World War where the Dutch queen Beatrix and prince Willem-Alexander will lay a garland at the National Monument on May 4, 2009 at the Dam Square in Amsterdam, The Netherlands, to commemorate all the dutch casualties of war since the Second World War. Security was tightened since the arrest of suspected terrorist after a bomb scare earlier today. AFP PHOTO / ANP / OLAF KRAAK ***netherlands out - belgium out*** (Photo credit should read OLAF KRAAK/AFP via Getty Images)

AFP AFP