Concerns have focused on drones spotted near the Bedminster golf course of president-elect Donald Trump, as well as sensitive infrastructure including electric transmission sights, rail stations and police departments.

Recently sightings have spread to parts of New York City and over the suburbs of Philadelphia. Nicole Malliotakis, a Republican Congress member representing Staten Island and parts of Brooklyn, told the House hearing that drones had been reported over the Verrazzano-Narrows Bridge, close to US military bases.

“They are flying over sensitive infrastructure, and the fact that we don’t know what they are, or who’s behind them, or what they’re doing is very concerning to me, particularly in a post-Chinese spy-ballon world,” she said, according to a report in the local Morristown Daily Record.