A top US official sought to quell growing concern Sunday over reported drone sightings in the country’s northeast, reiterating there was no known security threat as authorities monitor the situation. President Joe Biden’s administration has faced mounting criticism for not clearly identifying origins of the objects seen hovering over parts of New York and New Jersey. The criticism has come even from Biden’s own party, with top Democratic Senator Chuck Schumer calling Sunday for action to make it easier for federal, state and local authorities to work together to detect and if need be “bring down” any drone seen to pose a threat. Video footage of mysterious airborne phenomena recently has clogged social media, with spottings also reported in Maryland and Virginia. “Some of those drone sightings are, in fact, drones. Some are manned aircraft that are commonly mistaken for drones,” Homeland Security Secretary Alejandro Mayorkas said Sunday on ABC’s “This Week” program. “But there’s no question that drones are being sighted,” he said, noting there are more than one million registered across the United States. “I want to assure the American public that we are on it,” he said. “If we identify any foreign involvement or criminal activity, we will communicate with the American public accordingly. Right now, we are not aware of any.” Even as Mayorkas sought to reassure the public, Boston police announced Sunday that two Massachusetts men had been arrested the previous night for allegedly conducting a “hazardous drone operation” near the city’s Logan International Airport. State police were conducting a search for a third suspect, who authorities said fled the scene.