The following morning, 10 July 1995, Lieutenant Colonel Karremans made urgent requests for air support from North Atlantic Treaty Organization (NATO) to defend Srebrenica as crowds filled the streets, some of whom carried weapons. VRS tanks were approaching the town, and NATO airstrikes on these began on the afternoon of 11 July 1995. NATO bombers attempted to attack VRS artillery locations outside the town, but poor visibility forced NATO to cancel this operation. Further NATO air attacks were cancelled after VRS threats to bomb the UN's Potočari compound, to kill Dutch and French military hostages and to attack surrounding locations where 20,000 to 30,000 civilian refugees were situated. 30 Dutchbat were taken hostage by Mladic's troops.