Local leaders have started to push for answers on behalf of their residents.

A collective of 21 mayors from New Jersey wrote to the state’s governor on 8 December demanding a full investigation. The drone reports – and lack of satisfactory answers – had significantly alarmed half a million residents, they said.

One of those mayors was Ryan Herd of Pequannock Township, who said he was driven by the concerned calls he began receiving from residents at the end of November. Some asked whether the drones were spreading chemicals or if they had “the same capabilities to drop things on us as the ones in Ukraine”.

Mr Herd and nearly 200 other local leaders received a briefing at the New Jersey state police headquarters three days after they sent their letter, he said.

They heard from Homeland Security and Defense Department officals, who said the military or tech companies were not responsible for the objects in the night sky. They claimed to have no idea who was behind it, Mr Herd said.

“I blew my top,” he said. “This is America 2024 and you’re telling me drones are flying over our houses and you have no idea who’s flying them or where they’re from?”

Mayor Michael Melham of Belleville, New Jersey, also attended the briefing. He said they were told these drones of unknown origin were flying over critical infrastructure, but they posed no credible threat and would not be shot down.

“I don’t buy it,” he said.

His views seemed to be shared by President-elect Donald Trump, who has said “the government knows what is happening” – though he declined to say whether that declaration was based on a government briefing.

Trump has also said mystery drones “happen to be over Bedminster”, the home he owns in New Jersey. He said he had decided to cancel a weekend trip there as a result.

“How does that make my residents feel when the president-elect, who has a residence in New Jersey, is telling people that he’s not coming here that weekend?” Mayor Melham said.

With the demand for answers growing, federal authorities have provided advanced radar systems to some states, even as they repeat that the lingering drone mystery is no mystery at all.

“But I want to stress again,” Kirby said on Monday, “our assessment at this stage is that the activity represents commercial, hobbyist, (and) law enforcement drones – all operating legally and lawful – and/or civilian aviation aircraft.”

Additional reporting by Pratiksha Ghildial