South Korea says North Korea has test fired seven missiles into the sea.

A South Korean defense ministry official said Friday that the surface-to-air missiles launched from North Korea late Thursday flew into waters off the eastern coast.

North Korea routinely test launches missiles, rockets and artillery but the latest launch came as South Korea and the U.S. are conducting annual drills that Pyongyang calls an invasion rehearsal. Seoul and Washington say the drills are for defense.

North Korea fired two short-range missiles on the first day of the drills earlier this month and warned of "merciless" strikes against South Korea and the U.S. The military exercises are scheduled to continue until late April.