North Korea fires a ballistic missile in an apparent protest against the start of joint exercises between the U.S. and South Korea.

FOX's Jon Decker has more from the White House:

The North Korean missile was fired from a submarine off the East Coast of the country and according to South Korean defense officials, the missile flew for more than 300 miles, making it the longest flight of a North Korean submarine-launched missile.

U.S. Strategic Command said it had tracked the missile over and into the Sea of Japan.

Earlier this year, North Korea fired two other missiles from submarines, but they were believed to have exploded in midair after flying less than 20 miles.

At the White House, Jon Decker, FOX News.