WASHINGTON — U.S. military leaders on Sunday said they were in the dark about the exact nature and purpose of airborne objects shot down over the United States and Canada since Friday.

Unlike a balloon shot down off the coast of South Carolina Feb. 4, described by officials as spy aircraft, it’s unclear how the most recent objects stay aloft and move along, Gen. Glen VanHerck, commander of North American Aerospace Defense Command (NORAD) and the U.S. Northern Command (USNORTHCOM), said at a media briefing Sunday.

UFOs: U.S. shoots down flying object near Canadian border | CTV News

“I’m not going to categorize them as balloons,” he said. “We’re calling them objects for a reason. I’m not able to categorize how they stay aloft.”

After the briefing, a defense official added that there was “no indication of aliens or extraterrestrial activity with these recent takedowns.”

Earlier, when asked about that possibility, VanHerck had declined to rule it out. “I’ll let the intel community and the counterintelligence community figure that out,” he said.

An unidentified object shot down Sunday over Lake Huron — the fourth flying object in less than two weeks to have been downed over North American airspace — was described earlier Sunday by a senior administration official as an octagonal structure with strings hanging off but no discernible payload.

VanHerck described the objects shot down Friday, Saturday and Sunday by North American forces as being similar in size and shape. One issue in getting a better description, he said, is that fighter jets are traveling at relatively high speeds when eyes are put on them, at roughly 200 mph compared with objects that are aloft but otherwise nearly static.

Those three remained a mystery in contrast to the Feb. 4 takedown of aircraft believed to belong to the People’s Republic of China, Melissa Dalton, assistant secretary of defense for homeland defense and hemispheric affairs, said during Sunday’s briefing.

“The spy balloon from the PRC was of course different in that we know precisely what it was,” she said.

In a statement Sunday afternoon, the Pentagon confirmed that an F-16 fighter firing an AIM9x missile shot the latest object down at 2:42 p.m. at roughly 20,000 feet.

President Joe Biden gave the order based on the recommendations of military leadership after the object’s path and altitude raised concerns about risks to civil aviation. It was judged not to be a military threat, but it could have had surveillance capabilities, the statement said.

On Saturday evening, NORAD and U.S. Northern Command reported that fighter aircraft had been sent to investigate a radar-detected “anomaly” in airspace over Montana but said they were unable visualize any objects.

On Sunday, VanHerck said the overnight recurrence of an anomaly prompted military officials to develop a game plan as it was tracked Sunday to Lake Huron.

“The all-clear was given to engage the target and ultimately it was taken down about 15 nautical miles east of the Upper Peninsula in Lake Huron,” the general said.

The Pentagon said in its statement Sunday that NORAD had been able to track the anomaly visually and via radar. “Based on its flight path and data we can reasonably connect this object to the radar signal picked up over Montana, which flew in proximity to sensitive DOD sites,” it said.

The location of the shootdown was chosen to minimize risks to people on the ground and to improve chances to recover the debris, the statement said. There were no indications any civilians were hurt or otherwise affected, it said.