U.S. Shoots Down a Fourth Flying Object Over Lake Huron

U.S. and Canadian officials say the objects shot down on Friday and Saturday were also flying lower than the spy balloon, posing a greater danger to civilian aircraft, which prompted leaders to order them destroyed. Those two objects were flying over parts of Alaska and the Yukon that have few residents, and the third object downed on Sunday was over water, so risks posed by falling debris were minimal, they said.

The spy balloon that drifted across the United States flew much higher, at 60,000 feet, and did not pose a danger to aircraft. But any falling debris could have hit people on the ground, Pentagon officials said.

Throughout the weekend, officials said they were still trying to determine what the three objects were. The first, a Defense Department official said, is most likely not a balloon — and it broke into pieces after it was shot down on Friday. Saturday’s object was described by Canadian authorities as cylindrical, and American officials say it is more likely it was a balloon of some kind. Sunday’s object appeared unlikely to be a balloon, one official said.

NORAD radar tracked the first two objects for at least 12 hours before they were shot down. But Defense Department officials have never said whether they picked the objects up on radar before they neared American airspace.

U.S. officials said they are reviewing video and other sensor readings collected by the American pilots who observed the objects before their destruction. But the exact nature of the objects, where they are from and what they were intended for will not be confirmed until the F.B.I. and the Royal Canadian Mounted Police have the chance to thoroughly examine the debris, officials said.

While the incidents involved unidentified flying objects in the literal sense of the words, national security officials have discounted any thoughts that what the Air Force shot out of the sky represents any sort of extraterrestrial visitors. No one, one senior official said, thinks these things are anything other than devices fashioned here on Earth.

Luis Elizondo, the military intelligence officer who ran the Pentagon’s U.F.O. program until 2017, said that the Biden administration must find a way to balance vigilance over what is going on in the skies above America against “chasing our tail” whenever something unknown shows up — a tough task, he said.