What are the mystery drones flying over the US?

Mysterious drones have been swarming the night skies above New Jersey and other nearby states for a month. They have been spotted over several US military sites. They have been videoed over houses and apartment buildings. A swarm was seen following a US Coast Guard rescue boat at the same time that New Jersey police reported 50 drones arriving on land from the ocean. But no one seems to know who is piloting them, or whether it is a coordinated effort.

The incidents have drawn the attention of state governors and legislators, as well as members of the US Congress, and the FBI has launched an investigation, asking for the public to report sightings.

Witnesses describe the drones as being as loud as lawnmowers, with some approaching the size of a small car – significantly larger than a typical quadcopter or multirotor drone that anyone can purchase. “These are not necessarily just small, hobbyist unmanned aerial systems that you can buy for $2000,” says Daniel Gerstein at the RAND Corporation, a think tank in California. “These feel like they have longer range and are more sophisticated than what you can get at a hobby shop.”

Blurry nighttime videos have popped up all over social media sharing drone sightings in states such as New Jersey, Pennsylvania and New York, including one video showing drones over the Verrazzano-Narrows Bridge in New York City. The Federal Aviation Administration issued drone flight restrictions over the Trump National Golf Club and the Picatinny Arsenal Military Base in New Jersey after reports of drone activity over both. The sightings coincide with other drone swarms recently appearing near UK military bases where US Air Force squadrons operate.

On 10 December, the House Committee on Homeland Security held a hearing on drone threats with officials from the FBI, US Customs and Border Protection and US Department of Justice. The officials described the recent sightings as involving a possible mix of both rotor drones and fixed-wing drones but had little information to offer about what the drones are doing and who may be operating them. However, they said the drones do not yet represent a serious threat. In a separate briefing from the US Department of Homeland Security, the agency told lawmakers that some of the sightings may have mistaken aircraft for drones.

Ryan Herd, a town mayor from New Jersey, told ABC News Live that officials confirmed that these are not US military drones and that they are not operated by a US tech company.

Meanwhile in the UK, Vernon Coaker, a defence minister, told Parliament last month that authorities are investigating multiple drone incursions that occurred near several UK military bases starting on 20 November. Those bases support US Air Force squadrons that fly fighter jets, bombers and support aircraft.

“The common theme across all of these cases is that nobody has fully cracked the code on how to find, track and, if need be, take down small drones,” says Arthur Holland Michel, a journalist and author who writes about drones. “The second common theme is that if the person flying the drone is actively trying to avoid being identified, the challenges of countering that drone go through the roof.”

Radar and other sensors can track drones, but it is “still not practical to cover every inch of the country with detection and tracking systems”, which often leaves authorities “totally blind to drones in most of our airspace”, says Michel. “As a general rule, once a citizen has spotted a drone and reports it or films it with their phone, it’s too late [to take early action],” he says.

Gerstein says there is some uncertainty about who has the main authority and responsibility among local law enforcement and state and federal agencies to take action against such drones. And even if that is cleared up, it isn’t simple to figure out the best way to address them.

Many counter-drone measures exist for either shooting down drones directly – using missiles, lasers,  bullets and even other drones – or taking over control of suspicious drones and forcing them to land by using electronic warfare signals, says Gerstein. Such technologies have been commonly used during the drone-heavy war in Ukraine, while US Navy warships and other navy vessels have shot down dozens of drones threatening shipping in the Red Sea region.

“When it comes to shooting drones down, the most effective measures are often the most dangerous,” says Michel. “We simply can’t have law enforcement departments firing high-powered projectiles into the air, or activating military-grade signal jammers, every time a drone is spotted flying over [New Jersey].”