Unprecedented security measures were made by the Turkish government to safeguard the NATO summit from terrorist attacks . They especially feared a repetition of the Istanbul bombings of 2003 that killed more than 60 people . Their fear was proven by the arrest of 16 people in Bursa in early May on suspicion of planning to bomb the summit . Police seized guns , explosives , bomb-making booklets and 4,000 compact discs with training advice from Osama Bin Laden , and believed that the suspects were members of the radical Islamic group Ansar al-Islam , thought to be linked with al-Qaeda . On June 24 two bombs also exploded . One bomb went off in a bus in Istanbul killing 4 people ( including the bomber ) , the other outside a hotel in Ankara where US president George W. Bush would be staying . Additionally , on June 25 , explosives were found in a parked car at Istanbul 's main airport
Istanbul bombings of 2003
2003 Istanbul bombings
2004 Istanbul summit