SEOUL, South Korea (AP) — South Korea says North Korea has fired an unidentified projectile.

South Korea’s Joint Chiefs of Staff says the launch was made on Wednesday but gave no further details.

The launch came days after North Korean leader Kim Jong Un vowed to accelerate the development of nuclear weapons and threatened to use them if provoked in a speech at a massive military parade in Pyongyang.

The launch also appears to be the latest in a string of weapons tests by North Korea, which experts say are aimed at boosting its weapons arsenal and pressuring its rivals to ease international sanctions.