Inside the Secret Service 'shell game' to hide US presidents in plain sight

On 8 July, US President Donald Trump boarded Air Force One in plain sight of television cameras as he departed the Nato summit in Turkey.

But when the mighty Boeing aircraft left Ankara, the president had reportedly already been secretly spirited away via a catering truck to a C-32A, a military version of the Boeing 757, which flew the president to RAF Mildenhall in the UK.

Those left on board were unwitting decoys and had no indication that Trump was no longer travelling with them.

"That's very common," said Ronald Kessler, an author who has written extensively on the agency. "There's a long history of strategies to mislead anybody who might be trying to harm the president."

Robert McDonald, a former high-ranking Secret Service agent with experience working on presidential security details, told the BBC that smaller-scale deceptions are used frequently during motorcade operations.

These motorcades - which often include dozens of security and support vehicles, as well as ambulances and vans carrying White House reporters - typically include two "Beasts", as the enhanced limousine carrying the president is known.

While one vehicle carries the president, the other travels nearby as a decoy, switching locations while en route to the destination.

"It's what we call a shell game," said McDonald, who drove one of the vehicles during the Bush administration. "Even in DC if we headed to Andrews [Joint Base Andrews - where Air Force One flies from], those two limousines would change position, like under a highway overpass."