Mere days after an alleged Chinese spy balloon in American airspace drew national attention, U.S. officials say the military has shot down another “high-altitude object” over Alaska.

John Kirby, spokesman for the National Security Council, said the U.S. military had been tracking the object for roughly 24 hours.

He described it as “roughly the size of a small car,” but said U.S. personnel were unable to determine its purpose or its origin. He would not say whether it was a balloon like the one shot down last week, according to NBC News.

In a statement delivered at around 1:30 p.m. Central, Kirby said that U.S. Northern Command fighter aircraft had taken out the object “within the last hour.”

Some, such as Sen. Marco Rubio (R-FL), criticized the Biden administration for its apparent hesitancy to act in the earlier balloon incident.

“When was it spotted?” Rubio asked on ABC News’ This Week. “Why was it not brought down sooner over other areas? I’m open-minded to listening to the arguments they make about why it wasn’t dealt with sooner.”

Rubio is the chair of the Senate Intelligence Committee.

In the more recent incident, Kirby said, as per NBC News, “[t]he object was flying at an altitude of 40,000 feet and posed a reasonable threat to the safety of civilian flight.”

The average cruising altitude of a commercial flight is between 33,000 and 42,000 feet, according to USA Today.

Kirby said the object landed in U.S. waters off the coast of Alaska. Because that water is frozen at this time of year, Kirby believes the object can be retrieved and inspected by U.S. personnel, according to NBC News’ reporting on his statement.

The earlier alleged Chinese spy balloon was also located on Thursday, according to ABC News.

It is believed to be underwater near South Carolina, though — like the unidentified object in Alaska — it has not yet been retrieved. The South Carolina object, which was shot down on February 4, is estimated to be about 30 feet long, ABC News reported.

More information about the objects’ purposes, and about the likely origins of the object shot down over Alaska on Friday, is expected to be released in the coming days.