North Korea has fired at least one projectile in waters off Japan, according to South Korea's military.
It was launched early Tuesday morning and landed in the Sea of Japan also known as the East Sea.
Earlier this month it launched what it said were new cruise missiles, and also fired ballistic missiles in the same waters.
Tuesday's launch comes days after North Korea expressed willingness to engage in talks with the South.
Japanese media quoted the defence ministry as saying that the projectile may have been a ballistic missile, which is banned under United Nations sanctions.
South Korea's Joint Chiefs of Staff said they were monitoring the incident together with US officials.