WASHINGTON—Amid a baffling series of incidents in which the U.S. has shot down three unidentified flying objects, the White House said Monday it would create a team expected to study airborne objects and the potential security and safety risks they pose.

The new group, created at the behest of national-security adviser Jake Sullivan, would comprise elements of the Pentagon, the Federal Aviation Administration, the Department of Homeland Security and other government agencies, said U.S. officials.

The group will look at the “broader policy implications” of the objects for detection, analysis and disposition, said John Kirby, a spokesman for the National Security Council, on Monday. “Every element of the government will redouble their efforts to understand and mitigate these events,” he said. 

The Pentagon shot down on Feb. 4 what it described as a large Chinese spy balloon that entered American airspace, triggering the Pentagon to begin looking more closely at other airborne objects. American jet fighters have shot down three unidentified flying objects, two in the U.S. and one over Canadian airspace, in recent days. Unlike the balloon, which was floating in excess of 60,000 feet in the air, all of the three objects were flying at much lower altitudes that could interfere with commercial and other air traffic, officials said. The last one was shot down over Lake Huron on Sunday. 

The new group was created at the behest of national security adviser Jake Sullivan.

Photo: Susan Walsh/Associated Press

Mr. Kirby said there are no other known unidentified objects floating over U.S. airspace on Monday. 

But U.S. officials said they couldn’t explain what the other three objects were, even after closely studying them in the air before shooting them down. Some U.S. officials, including Senate Majority Leader Chuck Schumer (D., N.Y.), on Sunday morning described the unidentified objects that had been shot down over Alaska on Friday and over Canada’s Yukon territory on Saturday as balloons. The U.S. military continues to call them all objects. Collection of the resulting debris has been stymied by severe weather and terrain, U.S. military officials said Monday. Officials believe the first debris will be pulled out of Lake Huron and quickly sent to the Federal Bureau of Investigation lab at Quantico, Va., for analysis. U.S. officials have so far declined to provide any imagery of the items. 

Mr. Kirby said President Biden was first given a briefing on the issue of unidentified aerial phenomena in his presidential daily briefing June 21, 2021. 

On Sunday, the head of U.S. Northern Command and the North American Aerospace Defense Command wouldn’t rule out that the airborne objects the Pentagon has been shooting down are connected to aliens or extraterrestrials. 

“I’ll let the intel community and the counterintelligence community figure that out, I haven’t ruled out anything,” said Gen. Glen VanHerck in a briefing late Sunday. “At this point, we continue to assess every threat or potential threats unknown that approaches North America with an attempt to identify it.”

“There is no, again, no indication of aliens or extraterrestrial activity with these recent takedowns,” said White House press secretary Karine Jean-Pierre on Monday. 

The Pentagon has said the objects have been unmanned, and they cannot yet explain how the objects are powered, contributing to the mystery of the airborne object. Military officials have declined to describe the objects as balloons even though some U.S. officials have described them that way. 

“I’m not going to categorize these balloons, we call them objects for a reason,” Gen. VanHerck said without elaborating, though he hinted that they could be some kind of a balloon floating by gas or a different kind of propulsion system. “These are objects.” 

The Pentagon last summer formed the All-Domain Anomaly Resolution Office, which has reviewed 366 reports of unidentified aerial phenomena, or what most people refer to as UFOs. Of those, 171 “demonstrated unusual flight characteristics or performance capabilities, and require further analysis,” according to a report by the Office of the Director of National Intelligence. 

Because the office is classified, the Pentagon wouldn’t say how much funding is allocated for the office, a Pentagon spokeswoman said Monday. The office is part of the Military Intelligence Program, which is composed of several offices and requested $26.6 billion for its fiscal year 2023 budget. 

Sen. Kirsten Gillibrand (D., N.Y.), who led the push in Congress to establish AARO and chairs the subcommittee on emerging threats within the Senate Armed Services Committee, said she intends to hold a public hearing on the matter.

The purpose of creating AARO, Ms. Gillibrand said, is to make sure that service members are no longer stigmatized for forwarding and reporting on unidentified aerial phenomenon, and to make sure there is no retaliation.

“That’s what the legislation requires,” she said. “And as a consequence, we’ve seen a huge uptick in reporting in the past year and a half.”

— Lindsay Wise contributed to this article.

Write to Gordon Lubold at gordon.lubold@wsj.com and Nancy A. Youssef at nancy.youssef@wsj.com