North Korea fired two short-range ballistic missiles into the East Sea on Saturday in its fourth such provocation in less than a week.

South Korea's Joint Chiefs of Staff said it detected the missiles fired from the Sunan area in Pyongyang between 6:45 and 7:03 a.m. The missiles flew some 350 kilometers and reached an altitude of about 30 kilometers with a speed of Mach Six.

The JCS said an in-depth analysis by South Korean and U.S. intelligence authorities is ongoing.

Similar launches were carried out last Sunday and on Wednesday and Thursday. 

Pyongyang has conducted 20 ballistic missile and two cruise missile tests so far this year.

The latest back-to-back launches are seen as a protest to joint drills by South Korea and the U.S. and a trilateral exercise also involving Japan held this week.

Following the Saturday incident, JCS chairman Kim Seung-kyum and commander Paul LaCamera of the South Korea-U.S. Combined Forces Command held discussions and shared intelligence.

The JCS strongly condemned the recent tests as a clear violation of UN Security Council resolutions and urged the regime to stop, even as it stands prepared against more provocations.