The South Korean military believes North Korea's firing of two short-range ballistic missiles from a Pyongyang airport early Monday was likely a test launch to improve accuracy and consecutive launch capabilities.

Speaking to reporters, a Joint Chiefs of Staff(JCS) official said that South Korean and U.S. intelligence authorities are conducting a detailed analysis on the motive behind the recent series of back-to-back launches.

The official said the military was in readiness mode after detecting signs of a ballistic missile launch, and that it is closely monitoring related movements in coordination with the U.S.

The JCS earlier said it detected two projectiles fired from Sunan airport at 8:50 and 8:54 a.m. toward the East Sea. They are known to have flown about 380 kilometers at an altitude of 42 kilometers with a maximum speed of around Mach 5. 

In Friday's test firing, two projectiles were launched with an interval of eleven minutes, which was shortened to four minutes on Monday.