The US military shot down an unknown flying object off the coast of Alaska on orders from President Biden after it posed a "reasonable threat" to the safety of civilian flights.

The object was roughly the size of a small car and was flying at 40,000ft.

The White House spokesman, John Kirby, stated that it was not yet known who owned the object, where it came from or its purpose, but that fighter pilots visually determined that it was not manned.

This marks the second time in a week that the US military has downed some type of flying object over US airspace.

The incident comes after the US shot down a suspected Chinese spy balloon off the Carolina coast, which has drawn criticism from China who has reserved the right to take further actions.