For the second time in a week, the US has shot down an uninvited object in its airspace.
This one was over the northern state of Alaska and comes just six days after a Chinese balloon was shot down off the coast of South Carolina.
Here's what we know about the latest incident.
Where was the latest one?
About as close to the middle of nowhere as you can get while remaining in the US.
The Federal Aviation Administration restricted flights over a roughly 26-square kilometre area off Alaska's Bullen Point, the site of a disused US Air Force radar station on the Beaufort Sea about 210 kilometres from the Canadian border, inside the Arctic Circle.
According to the White House, the object was taken down as it travelled north-east.
The area is about 1,300 kilometres north of the state capital of Juneau, but the Pentagon press secretary Brigadier General Pat Ryder stressed the object was "within US sovereign airspace over US territorial water".
The area is sparsely populated by indigenous communities and small towns that have sprung up around mine sites.
Travel in a straight line north across the Arctic Ocean and before you know it, you'll cross the pole and be heading south again.
What was it?
We don't know.
White House National Security Council spokesman John Kirby says he doesn't know either.
He did say that it "did not appear to be manoeuvrable", but he also avoided characterising it as a balloon or drone.
"We're calling this an object because that's the best description we have right now," he told a media conference.
"We do not know who owns it, whether it's state-owned or corporate owned or privately and we just don't know and we don't understand the full purpose."
The Pentagon also declined to provide much detail, saying only that US pilots who flew up to observe it determined it didn't appear to be manned.
We also know it was much smaller than the Chinese balloon.
Mr Kirby compared the size of the two vessels thus:
"[It] was roughly the size of a small car as opposed to a payload [of the Chinese balloon] that was like two or three buses sized."
When did the US discover it?
On Thursday (US time).
It was first picked up by North American Aerospace Defense Command on ground radar, before two fighter aircraft were dispatched to take a closer look.
After this, President Joe Biden was notified.
It was then shot down about 1:45pm on Friday, Washington time, or 5:45am on Saturday, AEDT.
Why was it shot down so quickly?
Mr Kirby says it was destroyed because it was flying at about 40,000 feet (13,000 metres) and posed a "reasonable threat" to the safety of civilian flights.
Despite being remote, the skies above Alaska are busy, owing to mountainous terrain that restricts road travel.
However, most of the air traffic is concentrated in the state's south-west, around the cities of Juneau and Anchorage.
Mr Kirby said there was not any knowledge that it was engaged in surveillance.
This is in contrast to the balloon, which the White House claimed was a Chinese spy balloon, even as it declined to shoot it down over mainland US.
What did they shoot it down with?
Brigadier General Ryder said an F-22 fighter plane based at Joint Base Elmendorf-Richardson — near Anchorage in the state's south — shot down the object using an AIM-9X short-range air-to-air missile.
The same type of missile, known as a Sidewinder, was used to take down the balloon off South Carolina.
Will it be retrieved?
Several US military helicopters are already on their way.
While the object fell off the coast, the White House said the Beaufort Sea was frozen and officials expected they could recover debris faster than from last week's balloon.
Potentially complicating the recovery though are the harsh conditions in the area.
At this time of year there are only about six and a half hours of daylight every 24 hours.
Daytime temperatures on Friday were about -27 degrees Celsius.
Does this happen often?
No.
Apart from last week.
On Saturday, the US shot down a suspected Chinese spy balloon off the South Carolina coast after it traversed sensitive military sites across North America. China insisted the flyover was an accident involving a civilian craft and threatened repercussions.
The Pentagon said the balloon was part of a large surveillance program that China has been conducting for "several years".
What has Canada said?
Given the location of the incident near the international border, Canadian officials were informed, but were not involved in the decision to take the object down.
Canadian Prime Minister Justin Trudeau said he was briefed on the object and supported the US decision to take it down.
"I was briefed on the matter and supported the decision to take action," Mr Trudeau tweeted.
"Our military and intelligence services will always work together" to keep people safe, he added.
US Secretary of Defense Lloyd Austin also held a bilateral meeting with Canadian Minister of National Defence Anita Anand at the Pentagon.
