What we know about mysterious drones over New Jersey and other states

Dozens of people have reported seeing drones over New Jersey since 18 November

US aviation authorities have announced a temporary ban on the use of drones in nearly two dozen cities of New Jersey until mid January.

But mystery continues to swirl after nearly a month of drone sightings over New Jersey and other US states, alarming some residents.

Authorities have been unable to provide definitive answers about these sightings, saying only that the flying objects are not believed to pose a danger to the public or national security.

On Sunday, Homeland Security Secretary Alejandro Mayorkas confirmed the sightings included drones, as well as manned aircraft commonly mistaken for drones.

He added that he knows of "no foreign involvement" to do with the unmanned aerial vehicles.

Some lawmakers have criticised the government's handling of the drone reports and the lack of public information.

The drone reports have prompted a wide-range of baseless conspiracy theories, including that they are searching for nuclear weapons, radioactive "dirty bombs" or are form part of an impending invasion by aliens.

Here's what we know.

Where have drones been spotted?

Dozens of drone sightings have been reported over New Jersey since 18 November, but others have been reported around the US north-east.

Some of the flights were spotted near Picatinny Arsenal - a sensitive military research facility - as well as near President-elect Donald Trump's golf course in the town of Bedminster, New Jersey.

The Federal Aviation Administration (FAA) has since issued temporary restrictions prohibiting drone flights over 22 cities including Bedminster and Picatinny until 17 January.

Sightings have also been reported in several other states:

• In New York City, several drones were reported flying over the Bronx on 12 December

• Stewart Airfield in New York state had to shut down for about an hour on 13 December because of drone activity, Governor Kathy Hochul said

• In Connecticut, police confirmed "suspicious drone activity". A drone detection system is now in use near the towns of Groton and New London

• In Maryland, former Republican Governor Larry Hogan said he saw what appeared to be "dozens" of drones over his home in Davidsonville

• In Massachusetts, two men were arrested on 14 December after a "hazardous drone operation" near Logan International Airport's airspace in Boston, police said

• Multiple sightings have been reported in eastern Pennsylvania, including over Philadelphia

• In October, the Wall Street Journal reported that mysterious drones were seen for 17 days near US military facilities in Virginia

• In Ohio, a US Air Force base was briefly closed on 13 December after small drones were detected flying nearby. More drones were reported on 16 and 17 December, although the airbase's operations were not impacted

In late November, drones were also spotted over three US airbases in the UK, with British defence sources telling the BBC suspicion had fallen on a "state actor".

Drones were also reported near the Ramstein US military airbase in Germany in early December.

• Are mystery drones above US bases in England something sinister?

What have investigators said about the drones?

US President Joe Biden has said that there is "nothing nefarious" about the drone sightings, and "no sense of danger".

In an earlier call with reporters, officials from several US agencies said there was no evidence of any threat to public safety.

"I think there has been a slight overreaction," an official from the FBI said.

The homeland security secretary told ABC News on Sunday he knows of "no foreign involvement with respect to the sightings in the north-east".

"And we are vigilant in investigating this matter," he said.

Mayorkas added: "If there is any reason for concern, if we identify any foreign involvement or criminal activity, we will communicate with the American public accordingly."

Following a closed-door briefing on 17 December, Connecticut representative Jim Himes said that senior defence and law enforcement officials had told lawmakers that "there is zero evidence of laws being broken" by the drones.

He added that the "vast majority" of sightings were normal aircraft or drones being operated lawfully.

Himes said that "millions" of unregistered drones were operating across the US, in addition to 800,000 registered drones that weigh more than half a pound.

What are these flying objects?

Following a briefing with the Department of Homeland Security on 11 December, New Jersey assemblywoman Dawn Fantasia said the drones appeared to avoid detection by traditional methods such as helicopter and radio.

Fantasia said the aircraft were up to 6ft (1.8m) in diameter, travelling with lights turned off and "operate in a co-ordinated manner".

Secretary Mayorkas told ABC that an explanation for the uptick in drone sightings could be to do with a change in federal law last year that allowed drones to be flown at night.

"That may be one of the reasons why now people are seeing more drones than they did before, especially from dawn to dusk," he said.

A joint statement released by the Department of Homeland Security, FBI, FAA and defence department on 16 December said the sightings are a "combination of lawful commercial drones, hobbyist drones, and law enforcement drones, as well as manned fixed-wing aircraft, helicopters, and stars mistakenly reported as drones."

"We have not identified anything anomalous," the statement said, adding that the government still recognises "the concern among many communities."

President-elect Donald Trump, for his part, claimed that the "government knows what is happening".

"For some reason, they don't want to comment," he added. "I think they'd be better off saying what it is our military knows and our president knows."

While he declined to answer whether he had been briefed on the sightings, Trump said that he "can't imagine it's the enemy."

Where are they coming from?

It is unclear who might be operating them.

New Jersey Republican representative Jeff Van Drew said that the drones were coming from an Iranian "mothership" in the Atlantic, while Illinois Democrat Raja Krishnamoorthi said there was a "non-trivial" chance that China could be involved.

The Pentagon, White House and homeland security department have all insisted that there is no foreign origin for the objects.

A northern California man was charged on with flying a drone over and taking pictures of Vandenberg Space Force Base, located near Santa Barbara, on 30 November.

The man, 39-year-old Chinese national Yinpiao Zhou was arrested just before he boarded a flight to China.

But there has been no suggestion this incident has any connection with the spate of drone reports on the other side of the country.

The Pentagon says there is no foreign origin for the objects

Can the drones be stopped?

President-elect Trump has suggested the drones couldn't be flying without the government's knowledge.

"Let the public know, and now," he wrote on his Truth Social media platform. "Otherwise, shoot them down."

Senator Richard Blumenthal, a Connecticut Democrat, also said the drones should be shot down.

Shooting down drones is illegal, however.

New York State Governor Hochul has called on the federal government to allow states to crack down on the drones.

Senate majority leader Chuck Schumer has requested that federal officials send drone detection systems to New York and New Jersey.

In a statement, the FAA warned that drone operators who conduct unsafe or dangerous operations could face fines of up to $75,000 (£59,000) and have their drone pilot certificates revoked.