White House spokesman John Kirby told reporters many details were unknown about the object but the United States expected to recover the object after it landed in US territorial waters.
It was unclear where the object came from, Kirby said.
"We don't know who owns this object," he said.
He said the object went down on the far northeastern part of Alaska near the Canadian border.
He said the US pilot's assessment was that no human was onboard.
The United States on February 4 shot down what it said was a Chinese high-altitude surveillance balloon that transited the United States.
Kirby was careful not to classify the object as a balloon.
He said the knowledge about the new object and its track first came to US attention on Thursday night.
The Federal Aviation Administration (FAA) said on Friday it closed some airspace in northern Alaska to support Department of Defense activities.
The White House said on Friday the US military shot down an object off northeast Alaska that was about 40,000 feet up in the air and could have posed a "reasonable threat" to civilian aircraft.
The FAA issued a notice that it had closed some airspace around Deadhorse, Alaska.
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