The launch came hours after a senior North Korean diplomat announced that North Korea and the United States have agreed to resume working-level nuclear negotiations this weekend.
North Korea carried out another projectile launch on Wednesday, the South Korean military and Japan's Coast Guard said, a day after North Korea announced it will hold working-level talks with the United States at the weekend.
South Korea's Joint Chiefs of Staff (JCS) said North Korea fired an unidentified projectile on Wednesday morning from around Wonsan, in southeast Kangwon province, towards the sea to the east.
Japan's Coast Guard said in a statement North Korea had launched what appeared to be a missile and urged vessels to pay attention to further information and not to approach any debris.
Japan's PM condemns missile launches
Japanese Prime Minister Shinzo Abe on on Wednesday strongly condemned North Korea's latest launch of ballistic missiles, saying it was a violation of United Nations resolutions.
Abe told reporters Pyongyang had launched two ballistic missiles earlier in the day.
The launch came a day after North Korea announced it would hold working-level talks with the United States at the weekend.
Ninth launch since last Trump-Kim meeting
The launch was North Korea's ninth since US President Donald Trump and North Korean leader Kim Jong-un met at the heavily guarded Demilitarized Zone between the two Koreas in June.
It came hours after Pyongyang announced it had agreed with the United States to hold working-level talks on Saturday, a development that could potentially break months of stalemate.
Talks aimed at dismantling North Korea's nuclear and missile programmes have been stalled since the second summit between Trump and Kim in Vietnam in February ended without a deal.
Trump has played down North Korea's recent series of short-range launches, saying in September the United States and North Korea "didn't have an agreement on short-range missiles" and that many countries test such weapons.
"North Korea has recycled its carrot-and-stick strategy against the US multiple times with great success," said Lee Sung-yoon, Professor of Korean Studies at The Fletcher School at Tufts University.