"North Korea fired unidentified projectiles from Wonsan ... towards the East Sea (Sea of Japan) this morning," the South's Joint Chiefs of Staff said without providing further details.

"Our military is monitoring the situation for additional launches and maintaining a readiness posture," the JCS said in a statement.

The launch came a day after the North's Vice Foreign Minister Choe Son Hui said that Pyongyang had agreed to hold working-level talks with Washington later this week.

The two sides will have "preliminary contact" on October 4 and hold negotiations the following day, Choe Son Hui said in a statement carried by the official Korean Central News Agency.

US State Department spokeswoman Morgan Ortagus later confirmed the talks, which she said would happen "within the next week".

Negotiations between Pyongyang and Washington have been gridlocked since a second summit between North Korea's Kim Jong Un and President Donald Trump in February ended without a deal.

The two agreed to restart dialogue during an impromptu meeting at the Demilitarized Zone dividing the two Koreas in June, but the North's anger at a US refusal to cancel joint military deals with South Korea put the process on hold.