SEOUL, South Korea >> North Korea today fired a projectile into the waters off its east coast, South Korea’s military said, in an apparent missile test that comes days after Washington and Seoul began huge military drills that Pyongyang insists are an invasion rehearsal.

It was not immediately clear what was fired, but Pyongyang has staged a series of missile test-launches of various range in recent months. The ramped-up tests come as leader Kim Jong Un pushes for a nuclear and missile program that can deter what he calls U.S. and South Korean hostility toward the North.

Seoul and Washington call their military drills on the Korean Peninsula, which remains in a technical state of war because the 1950-53 Korean War ended with an armistice and not a peace treaty, defensive and routine.

The South’s Joint Chief of Staff said in a statement that Monday’s launch was made in the Tongchang-ri area in North Pyongan province. The area is the home of the North’s Seohae Satellite Station where it has conducted prohibited long-range rocket launches in recent years.

The North hates the military drills, which run until late April and which analysts say force its impoverished military to respond with expensive deployments and drills of their own. An unidentified spokesman for the North’s General Staff of the Korean People’s Army said last week that Pyongyang’s reaction to the southern drills would be the toughest ever but didn’t elaborate

North Korea test-launched a new intermediate-range missile in February and conducted two nuclear tests last year. There has also been widespread worry that the North will conduct an ICBM test that, when perfected, could in theory reach U.S. shores. Washington would consider such a capability a major threat.

The United States has 28,500 troops stationed in South Korea as a deterrent against a potential aggression from the North.