A 41-year-old man from France is being questioned after "what appears to be a firearm" was discovered in a bin at Gatwick airport, Sussex Police said.
The airport's North Terminal was evacuated following a subsequent security alert, but has now been re-opened.
A major security alert at Gatwick was sparked by a man "discarding an item" at the airport, police say.
The man was arrested and the bomb squad was called following the incident at around 9.30am on Saturday morning.
Detective Superintendent Nick May said it was "too early to say what the item may be".
"Given the events in Paris on Friday evening, there is heightened awareness around any such incident and it is best that we treat the matter in all seriousness," he added.
The Democratic presidential candidate may also have shown his cards on his choice of running mate.
The US president also shared a post on Twitter accusing Dr Anthony Fauci of misleading the public over hydroxychloroquine.
Fears over an impending second wave of coronavirus dominates Wednesday’s front pages.