"North Korea kicked off drills of the same kind two weeks earlier than last year," the South Korean Joint Chiefs of Staff spokesman, Jeon Ha-kyu told the agency.
The missile testing began at 4:20 p.m. local time, over the course of 50 minutes, and saw them fly about 200 kilometers before landing in the sea, according to the agency.
Sunday also marks the 67th anniversary of the Korean People's Army (KPA), North Korean news agency KCNA reported.
On Saturday, North Korean leader Kim Jong-un observed the test of an anti-ship rocket.
"The ultra-precision anti-ship rocket blasted off from a rocket boat. The intelligent rocket precisely sought, tracked and hit the 'enemy' ship after flying there safely," KCNA reported on Saturday.
Washington and Seoul have repeatedly blamed Pyongyang for developing rocket capabilities that they say are required for the creation of an effective inter-continental ballistic missile.