SEOUL » North Korea has test fired seven short-range missiles into the sea, South Korean officials said Friday, in the latest such tests launched during ongoing South Korea-U.S. military drills.

The surface-to-air missiles launched late Thursday flew into waters off the country’s eastern coast, said a South Korean defense official who requested anonymity because of official policy.

A South Korean Joint Chief of Staff officer, who also did not want to be named citing office rules, said North Korean leader Kim Jong Un inspected the missile tests but he refused to say how he obtained the information. Kim occasionally guides his military’s weapons tests, according to Pyongyang’s state media.

North Korea routinely test launches missiles, rockets and artillery but the latest launch came as the country reacts angrily to the annual springtime military drills between South Korea and the U.S. Pyongyang says the drills are aimed at practicing toppling its government, though Seoul and Washington say the training is purely defensive.

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 exercises will continue until late April.

In a legacy from the 1950-53 Korean War, the U.S. stations about 28,500 soldiers in South Korea as a deterrent to possible aggression from North Korea.

Earlier this year, North Korea told the U.S. that it was willing to impose a temporary moratorium on its nuclear tests if Washington cancelled the drills, but the U.S. rejected the overture.

The North conducted atomic bomb tests in 2006, 2009 and 2013 and outside analysts say a fourth test would put the country a step closer toward its goal of manufacturing warheads small enough to be mounted on a missile that can hit the U.S.

Associated Press writer Kim Tong-hyung contributed to this report.