Drones are still being spotted across New Jersey and other U.S. states — and Homeland Security Secretary Alejandro Mayorkas offered a possible explanation for the recent uptick in mysterious drone activity.

"There are thousands of drones flown every day in the United States, recreational drones, commercial drones," Mayorkas said Sunday on ABC's This Week with George Stephanopoulos. "In September of 2023 the Federal Aviation Administration, the FAA, changed the rules so that drones could fly at night, and that may be one of the reasons why now people are seeing more drones than they did before, especially from dawn to dusk," Mayorkas explained as he assured the American people that DHS is investigating.

Unexplained drone activity cause airspace to be closed for nearly four hours over the weekend at Wright-Patterson Air Force Base in Ohio, over one of the most critical Air Force bases in the U.S. In New York, runways at Stewart International Airport in Orange County were closed for about an hour because of drone activity.

The federal government is now sending drone detection systems to New York state following Gov. Kathy Hochul's request for more resources to help address the bout of recent reported sightings in her state.

"I am grateful for the support, but we need more. Congress must pass a law that will give us the power to deal directly with the drones," Hochul said in a post on X.

It's not clear if neighboring New Jersey will receive the same detection systems after Gov. Phil Murphy asked President Biden for additional resources last week to investigate what, or who, is behind unexplained drones that have been seen flying over his state in recent weeks.

"It has become apparent that more resources are needed to fully understand what is behind this activity," Murphy wrote in the Dec. 12 letter to the president and shared in a post on X on Friday. "The continued reporting of [unmanned aircraft systems] activity has raised more questions than answers and prompted an outcropping of conspiracy theories across social media and other platforms," he added.

Last Wednesday the Pentagon rejected claims made by Republican Rep. Jeff Van Drew of New Jersey that the drones are coming from an "Iranian mothership" off the East Coast.

"There is no Iranian ship off the coast of the United States, and there's no so-called mothership launching drones toward the United States," Pentagon press secretary Sabrina Singh told reporters Wednesday.

What are the details of the reported drone sightings?

Sightings of large, low-flying drones have been reported by residents in several states over the past few weeks, first sprouting up in New Jersey.

The unusual drone activity first raised questions after initial reports that they were spotted near the Picatinny Arsenal, a U.S. military research and manufacturing facility in Morris County. Since Nov. 13, 11 sightings have been confirmed over the facility.

Drones were also spotted over President-elect Donald Trump's Bedminster golf course, prompting the Federal Aviation Administration to extend temporary flight restrictions over the area.

Residents are becoming increasingly concerned, and elected officials are demanding answers as they've have grown frustrated by the lack of information from federal authorities, who say they are baffled.

The drones, according to witnesses, emit a loud humming sound and are estimated to be about 6 feet long. They fly only in the evening, from around dusk until about 11 p.m. ET.

Drone use for recreational and commercial purposes is allowed in the state, but operators have to follow local regulations and FAA flight restrictions. Most of the mysterious drones that have been spotted recently are larger than the drones available to hobbyists.

The drones have been seen flying in groups near critical infrastructure, including water reservoirs, power lines, railroads, highways, police departments and military installations.

There have been additional reports of sightings in Pennsylvania and over New York's Staten Island.

Are the drones dangerous?

The FBI is currently leading the investigation to uncover the mystery surrounding the drones’ origin and purpose. Local and state officials and DHS are also part of the investigation.

The FBI and DHS released a joint statement last Thursday that said in part, "We have no evidence at this time that the reported drone sightings pose a national security or public safety threat or have a foreign nexus. The FBI, DHS and our federal partners, in close coordination with the New Jersey State Police, continue to deploy personnel and technology to investigate this situation and confirm whether the reported drone flights are actually drones or are instead manned aircraft or otherwise inaccurate sightings."

The Pentagon said it was aware of the unexplained drone activity. “We have no evidence that these activities are coming from a foreign entity or the work of an adversary,” the Pentagon's Singh told reporters Wednesday. “We’re going to continue to monitor what is happening. At no point were our installations threatened when this activity was occurring.”

New Jersey Gov. Murphy has also said the drones over New Jersey don’t appear to be a threat to public safety, but that it’s not known who is piloting them and why they’re there.

"The most important point to say is we don't see any concern for public safety," he said at a press conference last Monday.

Murphy said he’s taking the situation “deadly seriously” because of the sophistication of the drones.

“The minute you get eyes on them, they go dark,” Murphy said of the drones, adding, “We’re obviously most concerned about sensitive targets and sensitive, critical infrastructure. We’ve got military assets, we’ve got utility assets, we’ve got the president-elect’s, one of his homes, here. This is something we’re taking deadly seriously. I don’t blame people for being frustrated.”

The Warren County Police Chiefs Association in New Jersey disagrees with the assessment that the drones pose no threat. "We are shocked by the lack of response or update from Federal and State officials," Chief Scott Robb wrote in a statement posted on X last Tuesday. "It is our stance that just the unidentified drone flying over us is a threat in itself."

Last Friday, an intelligence bulletin was reportedly circulated by the New Jersey Division of Fire Safety advising firefighters to stay clear of landed or crashed drones and to immediately contact the nearest bomb squad as well as the FBI. Yahoo News reached out to the New Jersey Division of Fire Safety to confirm authenticity of the bulletin and did not immediately hear back.

What has the FBI uncovered so far?

In Washington last Tuesday before a Department of Homeland Security subcommittee, Robert Wheeler Jr., assistant director of the FBI’s Critical Incident Response Group, faced questions from frustrated lawmakers.

"You're telling me we don't know what the hell these drones in New Jersey are?" Rep. Tony Gonzalez, a Republican from Texas, asked Wheeler.

“That's correct,” Wheeler replied.

Fellow Republican Rep. August Pfluger of Texas also asked Wheeler whether there is a risk to public safety. “Are we concerned there are nefarious intentions that could cause either an actual security or public safety incident?” Pfluger asked.

“There's nothing that is known that would lead me to say that,” Wheeler said. “But we just don't know. And that's the concerning part of it.”

On Dec. 3, the FBI’s field office in Newark asked for help from the public to report any information related to the recent drone sightings in areas along the Raritan River.

"Witnesses have spotted the cluster of what look to be drones and a possible fixed-wing aircraft. We have reports from the public and law enforcement dating back several weeks," the FBI field office said in a release.

Frustration grows among local lawmakers and officials 

Dozens of New Jersey mayors and lawmakers met with state police and Homeland Security officials last Wednesday, but many say they left with more questions than answers.

New Jersey state Sen. Holly Schepisi said she felt discouraged after the meeting. "For the federal government to not dedicate every defense resource needed to identify the origin and purpose of these drones in the most densely populated state in the nation is inexplicable and completely unacceptable," Schepisi said. "From a bipartisan perspective, most of the legislators in attendance shared the same view. We are going to have to work together and force the powers that be in D.C. to actually wake up and pay attention to the residents of New Jersey."

Montgomery Township Mayor Neena Singh said, "How can we, in 2024, not know where these drones are taking off from and where they're landing? That to me, doesn't make any sense."

Before the meeting, New Jersey state Sen. Jon Bramnick this week called for a limited state of emergency. "The State of New Jersey should issue a limited state of emergency banning all drones until the public receives an explanation regarding these multiple sightings," Bramnick said in a statement released Tuesday.