North Korea fired two unidentified projectiles, believed to be ballistic missiles into the East Sea on Thursday, the South Korean Joint Chiefs of Staff (JCS) said in a statement.
The launch comes a day after it fired two short range cruise missiles from a land-based launcher.
The projectiles were fired from the North's eastern South Hamgyong Province earlier in the morning, according to the JCS. "Further information is under analysis by South Korea-US intelligence authorities," the JCS said in a statement.
The United States brushed off the cruise missile launches as part of "normal testing" not banned under UN sanctions resolutions, with President Joe Biden saying, "Nothing much has changed."
While cruise missiles are not banned under UN Security Council resolutions on North Korea, ballistic missiles are subject to the international sanctions.
Ballistic missiles have a much longer range than cruise missiles of the same size and move quickly along their flight path.
North Korea's First Vice Foreign Minister Choe Son-hui said last week any contact and dialogue with the US can be possible only when Washington rolls back its "hostile policy" toward it.
North Korean leader Kim Jong-un held three meetings with former US President Donald Trump, but denuclearization talks remain stalled since the collapse of their Hanoi summit in February 2019.
Pyongyang wants sanctions to be lifted ahead of discussion on denuclearization. It has suspended long range ballistic missile launches and nuclear tests as a gesture of “goodwill.”