North Korea test-fired at least one ballistic missile on Sunday, the Yonhap news agency reported, the latest in a flurry of launches by the nuclear-armed state.
The agency said the South Korean Joint Chiefs of Staff detected one ballistic missile that had been fired toward the east, and was analyzing the incident.
North Korea tested weapon systems over three days earlier this month, including the firing of ballistic missiles and cluster bombs, state media said on April 8.
Analysts said these earlier launches signalled North Korea's latest rebuff of attempts by Seoul to repair ties.
Those included an expression of regret from Seoul over civilian drone incursions into the North in January.
The comments were initially described as "very fortunate and wise behaviour" by Kim Yo Jong, the powerful sister of North Korea's leader.
But this month a senior North Korean official described the South as "the enemy state most hostile" to Pyongyang, reviving a label previously used by leader Kim Jong Un.
