‘Do not pet’: Why are robot dogs patrolling Mar-A-Lago?

A robotic dog named “Spot” made by Boston Dynamics is the latest tool in the arsenal of the US Secret Service.

The device has lately been spotted patrolling the perimeter of President-elect Donald Trump’s Mar-a-Lago resort in Palm Beach, Florida.

They do not have weapons - and each can be controlled remotely or automatically - as long as its route is pre-programmed.