State media in North Korea say artillery and strategic rocket units have been put on combat ready status, with orders to prepare for strikes against the United States.
A statement from the Korean People's Army supreme command ordered "all artillery troops including strategic rocket units and long-range artillery units to be placed under class-A combat readiness", reports the BBC.
It said the units should be prepared to attack all American military bases in the Asia-Pacific region, including the US mainland, Hawaii and Guam, as well as South Korea.
Despite its successful long-range rocket launch in December, most experts believe North Korea is still years from developing a genuine inter-continental ballistic missile that could strike the continental United States.
South Korea's new president, Park Geun-hye, has urged North Korea to change course, amid the continuing threats of armed conflict.