Not many things with significant mass are drifting around tens of thousands of feet up.
An unidentified object may be the size of a “small car,” as one pilot report passed along by the Pentagon claims, but it’s not a car.
It may look “cylindrical,” as another states, but steel drums aren’t floating in the thin air at 20,000 feet.
If it doesn’t have an engine and wings, it’s a balloon, thousands of which have no military purpose.
The White House, so far, has been sure only that the objects weren’t alien spacecraft.