The South Korean military said the first launch, a ballistic missile, took place at 3 p.m. local time from an area around the city of Wonsan and flew about 450 kilometers into the sea.
A second projectile is also said to have been fired a couple of hours later.
The Japanese Prime Minister's Office said on X that both projectiles are suspected of being ballistic missiles.
The events come just days after the regime in Pyongyang reaffirmed its status as a nuclear power and rejected a UN resolution demanding that the country cease its nuclear weapons activities.
North Korea conducts repeated missile test launches.
