North Korea has threatened to wage a "full-fledged confrontation" against the US for what it calls "continued hostility".
In a statement carried by state media, the National Defence Commission in Pyongyang warned that it is prepared to conduct a nuclear test and carry out more long-range rocket launches.
The declaration follows the UN Security Council's condemnation of North Korea on Tuesday and expanded sanctions against the regime for launching a rocket in December.
North Korea said the launch was a peaceful satellite mission, but the US and others say it was actually a test of long-range missile technology.