SEOUL - Defense ministry of the Republic of Korea (ROK) said Tuesday that the Democratic People's Republic of Korea (DPRK) has made headway in its capability to weaponize nuclear program.

"(The DPRK's nuclear program) was at a developmental and experimental stage till 2010, but it has developed into a real threat in 2013 that can actually be weaponized and used at any time," the Defense Ministry said in a report to the parliamentary defense committee.

A week earlier, ROK's President Park Geun-hye urged the DPRK to give up its nuclear weapons program, denouncing that Pyongyang was still adhering to the nuclear weapons development despite oppositions from international communities in unison.

The DPRK said in March that it would restart operations at the Yongbyon nuclear complex by refurbishing and re-operating the five-megawatt graphite moderated reactor that had been mothballed and disabled since October 2007 under an agreement reached at the Six-Party Talks.

The Washington-based Institute for Science and International Security (ISIS) said last month that the roof size of the building in Yongbyong, which houses centrifuges for uranium enrichment, has doubled since March, hinting at an expansion of Pyongyang's nuclear capability.

Pyongyang test-fired a long-range rocket last December and conducted its third nuclear test in February, escalating tensions on the Korean Peninsula. The actions caused additional sanctions by the UN Security Council against the DPRK.

As the DPRK has strengthened its nuclear and missile capacity, Pyongyang would more likely misjudge Seoul's defense capability if Seoul regains its wartime operational control from Washington in December 2015 as planned, the defense ministry said.

ROK and the US have been reportedly discussing whether to reschedule the wartime operations control transition. Seoul handed over its operational control to the US-led UN troops during the 1950-53 Korean War, but it regained its peacetime operational control in 1994.