North Korea on Thursday fired three short-range rockets into the East Sea, raising military tension, Seoul’s Joint Chiefs of Staff said.

At around 5 p.m., the communist state fired three short-range projectiles with a range of some 190 km from the eastern coastal city of Wonsan.

“We are strengthening our readiness posture in case there are additional launches,” said the Defense Ministry in a press release.

Pyongyang fired a series of rockets and missiles in February and March this year in an angry response to the annual South Korea-U.S. military drills.

Some observers say that the North’s intentions in firing the projectiles may have been to strengthen internal unity in its military or probe South Korea and the U.S. to see how they respond to the provocative move.

By Song Sang-ho (sshluck@heraldcorp.com)