KNOCKED OUT: Major government and media websites in South and North Korea were shut down for hours Tuesday on the 63rd anniversary of the start of the Korean War.

KNOCKED OUT: Major government and media websites in South and North Korea were shut down for hours Tuesday on the 63rd anniversary of the start of the Korean War.

WHO HACKED THEM?: Seoul said its sites were hacked, while it was unclear what took out websites in North Korea. There were no initial reports that sensitive military or other key infrastructure had been compromised, and it wasn't immediately clear who was responsible.

TRADED ACCUSATIONS: North and South Korea have traded accusations of cyberattacks in recent years. Experts believe North Korea trains cyber warriors and that South Korea should be prepared against possible attacks.