North Korea fired two short-range missiles off the east coast into the sea on Monday, resuming testing after a three-month pause.
The missiles were launched from the eastern coastal city of Wonsan and flew 240km and reached 35km in altitude, South Korea's Joint Chiefs of Staff (JCS) said.
North Korea has launched a series of missiles from the area in the past.
The North appears to be continuing a firing drill that leader Kim Jong-un oversaw last Friday, JCS said.
Monday's launch was the first since North Korea fired what it called "super-large multiple rocket launchers" on 28 November.
South Korea's presidential Blue House said national security adviser Chung Eui-Yong held an emergency video conference with ministers of related agencies to analyse the latest test.
State media KCNA said North Korean leader Kim Jong Un supervised a military drill that simulated an attack on an island target. Source: KCNA via KNS
"The ministers expressed strong concern over North Korea's resumption of short-range missile launches in three months," the Blue House said in a statement.
"Such actions are unhelpful for efforts to ease tensions on the Korean peninsula and they urged North Korea to stop them."
JCS said it is monitoring for potential additional launches.
South Korea and the United States indefinitely decided to postpone joint military drills amid a growing coronavirus outbreak in South Korea that has now infected soldiers from both countries.
