The missiles were fired off from a location to the northeast of the eastern coastal city of Wonsan, according to a statement by South Korea's Joint Chiefs of Staff (JCS), Efe news reported.
The JCS said that one of the missiles was possibly launched from a submarine, which, if confirmed, would make it the first test of this kind Pyongyang carried out since the summer of 2016.
According to the JCS, the submarine-launched ballistic missile (SLBM) likely belonged to the Pukguksong (Polar Star) medium-range series, said to have nuclear capability.
The missile reached an estimated peak altitude of 910 kilometres (565 miles) and travelled a distance of approximately 450 kilometers before falling into the Sea of Japan, the JCS said.
North Korea's previous SLBM launch on August 24, 2016, involved a Pukguksong-1 missile that was fired from the same region where Wednesday's test took place.
This new test was also confirmed by the Japanese government.
Yoshihide Suga, a spokesperson for the Japanese government, told reporters that at least two projectiles (which appeared to be ballistic missiles) were fired and that one of them fell within Japan's EEZ, off the coast of the southwestern Shimane prefecture.
The first projectile, according to Suga, was launched at 7.17 a.m. Korean time, while the one that reached the EEZ was fired 10 minutes later.
These latest tests came a day after Pyongyang announced it would soon resume talks with the US on the Korean Peninsula's denuclearization.
A senior North Korean official said that negotiations would kick off again on Saturday following preliminary diplomatic contacts on Friday, though she failed to specify the planned location for these talks.
The resumption of negotiations which are set to be first held at a technical level was agreed upon by US President Donald Trump and North Korean leader Kim Jong-un during their summit at the inter-Korean border held on June 30.
( With inputs from IANS )