South Korea's military said on Thursday North Korea's recent statements regarding striking the U.S. territory of Guam are a challenge against Seoul and the U.S.-South Korea alliance.

Joint Chiefs of Staff spokesman Roh Jae-cheon told a media briefing South Korea was prepared to act immediately against any North Korean provocation, although the military had not spotted any unusual action in the North indicating provocation.

North Korea dismissed on Thursday warnings by U.S. President Donald Trump that it would face "fire and fury" if it threatened the United States as a "load of nonsense", and outlined detailed plans for a missile strike near the Pacific territory of Guam.