SEOUL, May 4 (Reuters) - North Korea has fired an unidentified projectile toward the sea off its east coast, South Korea's military said on Wednesday, about a week after the North vowed to develop its nuclear forces "at the fastest possible speed."

The launch, which marks the North's 14th major weapons test this year, comes days before South Korea's newly elected President Yoon Suk-yeol takes office on May 10.

Details of the projectile, including its flight range and altitude, were not immediately available. Japan's Coast Guard said it could be a ballistic missile.

Last week, North Korean leader Kim Jong Un pledged to speed up the development of his country's nuclear arsenal while overseeing a huge military parade as denuclearisation talks with the United States remain stalled.