An evacuation order has been lifted at NORAD headquarters in Colorado after five suspicious packages were removed.
Officials say employees became suspicious of the packages because something looked "out of place." They declined to elaborate.
Officials say NORAD's control room team was working at a backup location several miles away when the building was evacuated Thursday morning and no essential operations were disrupted.
The evacuation lasted about 4 1/2 hours, ending at about 2:30 p.m.
Officials say the packages were removed but are still undergoing tests.
NORAD is short for North American Aerospace Defense Command. The joint U.S.-Canadian command defends the skies over both nations.
A backup control room in Cheyenne Mountain is in use because of renovations at the headquarters building.