“We’re preparing for an enormous turnout,” said Matt McCool of the Secret Service's Washington Field office, who said more than 18 miles of “anti-scale fencing” would be erected and “multiple drones” would be in the air. The entire District of Columbia is normally a no-fly zone for drones.

Some 200,000 spectators are expected to attend to see military aircraft and tanks on Flag Day, which is also Trump's birthday.