North Korea on Wednesday threatened to unleash merciless retaliation over the ongoing South Korea-US joint military exercises and the United Nations sanctions for its nuclear test, Yonhap news agency reported. In a statement released by the Ministry of the People's Armed Forces, the North said that the armistice agreement that halted the Korean War (1950-53) and past South-North Korea nonaggression pacts are no longer valid, and all that remains is for Pyongyang to retaliate against aggressors. "Warmongers would be well advised to keep in mind that the DPRK is no longer restrained," the statement carried by the Korean Central News Agency (KCNA) said. The state news wire service added that "what is left to be done is (to push forth) an action of justice and merciless retaliation of the army and people of the DPRK." The DPRK stands for the Democratic People's Republic of Korea, the North's official name. The ministry also said the North has chosen the United States and South Korean military warmongers as targets for its all- out actions to defend its sovereignty and they will be the primary targets of merciless strikes. In the past, Pyongyang has threatened to turn Seoul and Washington into a "sea of fire," hinting it can use nuclear weapons. It pointed out that Pyongyang will never abandon its nuclear weapons that it says are critical to preserving peace and deterring aggression from foreign forces. It claimed that with its nuclear capability, the North can now effectively keep the U.S. and other big powers from resorting to high-handed tactics to force their will on others. The ministry said that whatever resolutions the U.N. Security Council (UNSC) adopts lack legitimacy since it has become a "voting machine bereft of impartiality and equity." The harsh statement comes as the North in recent weeks has stepped up its war of words against the annual Foal Eagle and Key Resolve military drills, and the UNSC's condemnation of its third nuclear test carried out on Feb. 12. Before the latest nuclear detonation, Pyongyang tested nuclear devices in 2006 and 2009.