The North Korea regime has fired two missiles as the annual US-South Korea drills began earlier today.
Officials in Seoul said two short-range missiles were fired into the ocean east of Korea, assumed to be in reaction to the joint drills.
While both the US and South Korea describe the drills as defensive, Pyongyang says they are a rehearsal for an invasion.
"If North Korea takes provocative actions, our military will react firmly and strongly so North Korea will regret it in its bones," Defence Minister Kim Min-seok said according to Reuters.
The North Korean military earlier on Monday condemned the joint exercises as "undisguised encroachment" on national sovereignty.
Aggression should be dealt with by "merciless strikes", it said in a statement on the KCNA news agency.