The object was much smaller than a huge Chinese balloon that crossed the United States last week and was shot down by a US fighter jet off the Atlantic coast on Saturday.
US fighter jet shot down an unidentified object drifting high over Alaska on Friday, the White House said, just six days after the downing of an alleged Chinese spy balloon sparked a fresh diplomatic rift with Beijing.
White House National Security Council spokesman John Kirby said it was unclear what the purpose or origin of the new object was, but said that it was taken down because, floating at 40,000 feet, it was a threat to civil aviation.
"The president ordered the military to down the object," Kirby said.
Questioned about the incident by reporters at the White House, Biden said the shoot-down "was a success."
Kirby said the object was much smaller than a huge Chinese balloon that crossed the United States last week and was shot down by a US fighter jet off the Atlantic coast on Saturday.
It was "roughly the size of a small car," he said.
"We do not know who owns it, whether state owned or corporate owned," he said. "We don't understand the full purpose."
Pentagon spokesman Brigadier General Pat Ryder said an F-22 Raptor used an AIM-9X missile to bring down the object -- the same aircraft and munition used to target the alleged Chinese spy balloon.
The incident took place amid a new alarm over what US officials say is an ongoing program by China to fly surveillance balloons to collect intelligence around the world.
The incident led US Secretary of State Antony Blinken to cancel an imminent trip to Beijing that had been long in planning and aimed at improving communications between the two rival superpowers.
Kirby said the new object was detected late Thursday, and shot down Friday afternoon Washington time.
It went down in northern Alaska near the Canadian border and fell over a frozen body of water, making recovery feasible, Kirby said.