Washington: White House on Friday (local time) confirmed that the US shot down a second 'high altitude object' over Alaska.

White House National Security Council spokesman John Kirby said that the Department of Defense shot down a "high altitude object" that was in Alaska's airspace in the last 24 hours.

"Department of Defence was tracking a high-altitude object over Alaska airspace in the last 24 hours. Fighter aircraft assigned to US Northern Command took down the object within the last hour," said Kirby.

Kirby said the object was flying at an altitude of 40,000 feet and "posed a reasonable threat to the safety of civilian flight."

"Out of the recommendation of the Pentagon, President Biden ordered the military to down the object," said Kirby.

However, he declined to identify the object's country of origin.

"We're calling this an object because that's the best description we have right now," Kirby said. "We do not know who owns it, whether it's state-owned or corporate-owned or privately-owned. We just don't know."

Kirby said the Biden administration does not know who owns the high-altitude object, saying it's unclear whether it's state-owned or privately owned.

He said the object fell within the United States' territorial space and fell in the Arctic Ocean on the northern side of Alaska.

It comes after the US shot down a Chinese "spy" balloon over its territorial waters last Saturday.

He also said it didn't appear that it had the ability to independently manoeuvre itself like the Chinese balloon that flew above the US for eight days before the US downed it off the coast of South Carolina.

"The first one was able to manoeuvre, and loiter, slow down, speed up," Kirby said. "It was very purposeful."

Kirby added that its debris field was "much, much smaller" than the balloon shot down last week off the coast of South Carolina.

The object, which the US learned about on Thursday evening, was described as "roughly the size of a small car," Kirby said.

He said a recovery effort will be made to learn more about the object.

Officials did not understand the full purpose of the object, Kirby added, saying the US expects that it will be able to recover the debris.

"A recovery effort will be made and we're hopeful that it'll be successful and then we can learn a little bit more about it," he said.

Kirby also added that the United States will not reach out to China over this new object.

Responding to a question on China purchasing land near US military bases, Kirby said, "We're always concerned about potential foreign collection near our military sites. We take that seriously, whether that's terrestrial related or whether it's from the air."