The Pentagon shot down an unknown object flying in US airspace off the coast of Alaska on Friday, White House officials said.
The object was flying at about 40,000 feet and posed a “reasonable threat” to the safety of civilian flights, said John Kirby, White House National Security Council spokesman.
Mr Kirby said that President Joe Biden ordered the military to down the object, which he described as roughly the size of a small car.
The object fell into US waters. No other details about what it was were immediately provided.
It is the second time in a week officials have downed some type of flying object over the US.
On Saturday, fighter jets shot down a suspected Chinese spy balloon off the coast of South Carolina.
Officials are still recovering debris from that object, shot down off the coast of South Carolina.
White House officials drew major differences between the two episodes.
Mr Kirby said it wasn't yet known who owned the object, and he did not say that it was a balloon.
Officials also couldn't say if there was any surveillance equipment on it and didn't know where it came from or what its purpose was.
Mr Kirby also said fight pilots visually examining the object ascertained that it was not manned.
The object fell into frigid waters and officials expected they could recover debris faster than from last week's massive balloon.
President Joe Biden issued the order but had wanted the balloon downed even earlier.
Military officials determined that bringing it down over land from an altitude of 60,000 feet would pose an undue risk to people on the ground.
China responded that it reserved the right to “take further actions” and criticised the US for “an obvious overreaction and a serious violation of international practice”.
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