TOMS RIVER, N.J. (AP) — Gov. Phil Murphy has asked the Biden administration to put more resources into an investigation of mysterious drone sightings that have been reported in New Jersey and nearby states.

Murphy, a Democrat, made the request in a letter Thursday, noting that state and local law enforcement remain “hamstrung” by existing laws and policies in their efforts to successfully counteract any nefarious activity of unmanned aircraft. He posted a copy of the letter on the social media platform X.

“This leaves action surrounding the (drones) squarely on the shoulders of the federal government,” Murphy said. “More federal resources are needed to understand what is behind this activity.”

Murphy and other officials have repeatedly stressed that there is no evidence that the aircraft pose a national security or a public safety threat, or have a foreign nexus. The Pentagon also has said they are not U.S. military drones.

The drones have drawn intense public concern and curiosity since residents first reported seeing them last month. Assemblywoman Dawn Fantasia said from four to 180 aircraft have been reported to authorities since Nov. 18, appearing from dusk till 11 p.m.

The flying objects have been spotted near the Picatinny Arsenal, a U.S. military research and manufacturing facility, and over President-elect Donald Trump’s golf course in Bedminster, but the number of reported sightings has grown greatly since then. Drones were also spotted in Pennsylvania, New York, Connecticut and other parts of the Mid-Atlantic region.

The FBI, Federal Aviation Administration and other state and federal agencies involved in the investigation have not corroborated any of the reported sightings with electronic detection, and reviews of available images appear to show many of the reported drones are actually manned aircraft. They also say there have been no confirmed sightings in restricted air space. It’s also possible that a single drone has been seen and reported more than once, officials said.

Some federal lawmakers have called on the military to “shoot down” the drones. The drones also appear to avoid detection by traditional methods such as helicopter and radio, according to a state lawmaker who was briefed by the Department of Homeland Security.

In one case, a medevac helicopter was unable to pick up a seriously injured car accident victim in Branchburg Township in Somerset County late last month due to drones hovering near the planned landing zone, according to NJ.com. The FAA said Thursday that it does not have a report on this incident.

Drones are legal in New Jersey for recreational and commercial use but are subject to local and FAA regulations and flight restrictions. Operators must be FAA certified.

Witnesses say the drones they think they have seen in New Jersey appear to be larger than those typically used by hobbyists.