North Korea fired two short-range ballistic missiles into the East Sea on Sunday, one at 1:20 a.m. and another at 1:30.
This is its second launch in just four days.
South Korea's Joint Chiefs of Staff believes the rockets to be Scud-C missiles,
given they flew a distance of around
500 kilometers, which is the Scud-C's estimated operational range.
The missiles were launched from the northern part of Kaesong city, just 20 kilometers from the border with the South.
Usually the North conducts missile launches from its eastern port city of Wonsan, around 130 kilometers
from the Military Demarcation Line.
A Joint Chiefs of Staff official said Sunday that the launch took place 20 kilometers closer to the South than the Wednesday launch, adding that a test-firing so close to the border is unprecedented.
The South Korean military believes that Pyongyang wants to display its ability to launch projectiles whenever and wherever it wants to.
The latest test firing is seen as an armed protest against annual U.S.-South Korea joint military exercises, scheduled to take place beginning Wednesday.
Pyongyang's National Defense Commission condemned the drills in a statement Saturday, as the USS George Washington aircraft carrier arrived in the southern port city of Busan on Friday for the drills.
Experts also believe the provocations come from concerns about the latest South Korea-China summit, as well as the recent U.S.-China business talks.
Sunday's firings mark the fourteenth time North Korea has launched rockets in 2014, and it is the sixth ballistic missile launch this year.
Kwon Soa, Arirang News.