North Korea fired multiple projectiles from its east coast early Thursday, according to South Korea's military.
The projectiles were launched from near North Korea's Hodo peninsula in South Hamgyung province, South Korea's Joint Chiefs of Staff said.
"Our military will keep monitoring for additional launches," the message said.
The launch comes six days after North Korea fired two short-range ballistic missiles, in what it said was a response to South Korea's decision to purchase U.S. weapons and continue joint military drills with Washington.
North Korea has said it could restart intercontinental ballistic missile and nuclear tests if Seoul and Washington go ahead with the exercises. Pyongyang has also said it may not resume working-level nuclear talks with the United States.
U.S. President Donald Trump has not responded to the latest launch, but shrugged off North Korea's launches last week as short-range missiles that "lots test."
"I have a good relationship with him. I like him. He likes me. We'll see what happens," Trump said earlier Thursday.
North Korea is banned from any ballistic missile activity under United Nations Security Council resolutions.