North Korea has claimed that it fired two missiles past South Korea's southeastern coastal city of Ulsan during a four-day military operation last week, a claim refuted by South Korea.

According to the North's Korean Central News Agency(KCNA) on Monday, the General Staff of the Korean People's Army(KPA) said it conducted the military operation in response to the Vigilant Storm aerial exercise jointly conducted by South Korea and the U.S.

The KPA gave a detailed account of a set of operations conducted between November 2 and 5, including the firing of two strategic cruise missiles just 80 kilometers off the coast of Ulsan.

South Korea's Joint Chiefs of Staff(JCS), however, countered the claim, saying not all of the North Korean reports are true and that it did not detect any cruise missiles in the region.

The JCS also said that despite the lack of reporting in the North on any anomaly in last week's launch of an intercontinental ballistic missile(ICBM), it stands by its evaluation that the missile failed mid-flight.

The KPA earlier said it will take "sustained, resolute and overwhelming" practical military measures in response to the allies' joint military drills.