North Korea said on Saturday that it would build more nuclear weapons in reaction to the United Nations Security Council resolution condemning its most recent nuclear test.
It also said it would respond militarily to any attempt by the US and other countries to isolate it or impose a "blockade", according to a statement from the foreign ministry reported by the official Korean Central News Agency.
It said that the enrichment of uranium for weapons was progressing.
South Korea's foreign ministry welcomed Friday's Security Council resolution on Pyongyang, saying that the resolution reflected the "common and decisive will" of the Security Council to eliminate North Korea's nuclear activities and halt the spread of weapons of mass destruction.
The government called on North Korea to accept this "clear and unambiguous" message from the international community.
The UN Security Council resolution was a reaction to North Korea's second atomic test, which took place May 25.
Resolution 1874 will expand the sanctions that were imposed in 2006 after North Korea's first nuclear test.