The US military is unsure what three flying objects it shot out of the skies over North America were - and how they were able to stay aloft.
President Joe Biden ordered another object - the fourth in total this month - to be downed on Sunday.
As it was traveling at 20,000ft (6,100m), it could have interfered with commercial air traffic, the US said.
A military commander said it could be a "gaseous type of balloon" or "some type of a propulsion system".
He added he could not rule out that the objects were extra-terrestrials. บาคาร่า350