North Korea declared Tuesday that it has fully resumed the operation of its uranium enrichment plant and the plutonium-producing reactor at the Yongbyon nuclear complex.

"All the nuclear facilities in Yongbyon including the uranium enrichment plant and 5 MW graphite-moderated reactor were rearranged, changed or readjusted and they started normal operation," the director of country's atomic agency told state run Korean Central News Agency (KCNA), according to Reuters.

The secretive communist state also warned that it won't hesitate to nuke the U.S. if Washington continued with its "hostile" policy, as HNGN previously reported.

"If the U.S. and other hostile forces persistently seek their reckless hostile policy towards the DPRK and behave mischievously, the DPRK is fully ready to cope with them with nuclear weapons any time," the official news agency reported, according to CNN.

The U.S. asked North Korea to refrain from "irresponsible provocation." White House spokesman Josh Earnest said that the international community will not accept North Korea as a "nuclear state" and that it should focus on fulfilling its international obligations instead of working on a nuclear program, TIME reported.

South Korea issued a stern warning to the North, threatening to respond in a proper and stern manner. "North Korea's possible launch of a missile or conducting a nuke test are serious provocations and military threats," South Korean Unification Ministry spokesman Jeong Joon-hee said on Wednesday, according to Yonhap news agency.

"So if the North makes such provocations, Seoul will respond to them by collaborating with the international community in a proper and stern manner," Joon-hee warned.