North Korea on Saturday threatened military action if the US tried to isolate it after the UN Security Council imposed widened sanctions against the reclusive communist state for a nuclear test in May. The North also vowed to start a programme to enrich uranium and to weaponise plutonium at its nuclear weapons plant,the Norths official news agency KCNA quoted its Foreign Ministry spokesman as saying. The sanctions resolution approved on Friday banned all weapons exports from North Korea and most arms imports into the state. It authorised UN member states to inspect North Korean sea,air and land cargo,requiring them to seize and destroy any goods transported in violation of the sanctions. A South Korean official said that North Korea may possibly respond to UN punishment with another nuclear test and maybe more missiles. They will never,never give up their nuclear weapons, said the official who asked not to be named. North Korea has raised tension in the region in the past months by test-firing missiles,restarting a plant to produce arms-grade plutonium and holding the May 25 nuclear test,which put it closer to having a working nuclear bomb. Two senior diplomats negotiating the UN resolution said the Chinese had never really clarified whether they intended to implement the new sanctions resolution. Chinas UN ambassador,Zhang Yesui,said the resolution showed the firm opposition of the international community to North Koreas nuclear ambitions,but he urged countries to exercise caution when inspecting North Korean cargo.