RONALD REAGAN NATIONAL AIRPORT, UNITED STATES
An airport policeman awaits a K-9 unit to check out a suspicious package at Ronald Reagan National Airport...
An airport policeman (L) awaits a K-9 unit to check out a suspicious package at Ronald Reagan National Airport, Arlington, Virginia, U.S., November 7, 2016. The day before the U.S. presidential elections there is heightened security due to an unspecified terrorist threat from Al Qaeda. REUTERS/Mike Theiler