North Korea has delivered a fresh round of rhetoric with claims it has "powerful striking means" on standby for a launch amid speculation the Pyongyang regime is preparing to test a medium-range missile during forthcoming national celebrations.
The declaration prompted President Barack Obama to call on North Korea to end its belligerence.
He warned the United States would take "all necessary steps" to protect its people. But he said that no-one wants to see a conflict on the Korean Peninsula.
Mr Obama spoke alongside UN Secretary-General Ban Ki-moon after the two met at the White House.
On the streets of Pyongyang, meanwhile, North Koreans celebrated the anniversary of leader Kim Jong Un's appointment to the country's top party post - one of many titles collected a year ago in the months after father Kim Jong Il's death.
The warning of a potential strike came from the Committee for the Peaceful Reunification of the Fatherland, a non-military agency which deals with relations with South Korea.
The statement is the latest in a series of warlike threats seen outside Pyongyang as an effort to raise fears and pressure Seoul and Washington into changing their North Korea policy.
Officials in Seoul and Washington say Pyongyang appears to be preparing to test-fire a medium-range missile designed to reach the US territory of Guam in the Pacific Ocean.
The missile has been dubbed the "Musudan" by foreign experts after the north-eastern village where North Korea has a launch pad. The missile has a range of 2,180 miles (3,500 kilometres).
Such a launch would violate UN Security Council resolutions prohibiting North Korea from nuclear and ballistic missile activity, and mark a major escalation in Pyongyang's stand-off with neighbouring nations and the US.