The U.S. shot down an object over Alaska. The government doesn't know yet what it was

The object was tracked over Alaska at an altitude of 40,000 feet, said John Kirby, a spokesman for the White House National Security Council. On Friday afternoon, fighter jets shot it down. (Brendan Smialowski/AFP via Getty Images)

U.S. fighter jets on Friday afternoon shot down a mysterious object about the size of a car that was detected about 40,000 feet over Alaska.

It's not yet clear what it was — the White House is describing it as a "high-altitude object." But the incident marks the second time in a week where dramatic action has been taken to shoot down something deemed to be a threat over the skies of America.