North Korea has the capacity to carry out a fourth nuclear weapons test whenever it chooses to do so, South Korea's senior negotiator for stalled denuclearization negotiations with Pyongyang said on Tuesday.
Nuclear envoy Cho Tae-yong told an audience in Seoul "the assessment of North Korea's nuclear capabilities is very grave, and we see it has the ability to carry out another round of nuclear tests whenever it wants in technological terms," the Yonhap News Agency reported.
Pyongyang carried out its third and most-powerful test to date in February. Experts believe at least one more underground explosion is necessary for the North to figure out how to miniaturize nuclear weapons for loading onto missiles.
"There are signs that the five-megawatt graphite moderated reactor has been in operation recently, the North is expanding nuclear enrichment facilities, and construction is underway for a small-scale light-water reactor," Cho said in ticking off the various areas where Pyongyang is advancing its ability to produce fissile material for warheads.
The head of the U.N. nuclear watchdog agency in an interview with Yonhap said another nuclear test by the North "or threat of another test, is very disturbing."
International Atomic Energy Agency Director General Yukiya Amano said: "We are always prepared to go back to North Korea when requested. But in order that the IAEA goes back to the North, a political agreement is essential."
Pyongyang has said it is willing to return to regional aid-for-denuclearization negotiations but only on an unconditional basis. It has also tried to get its erstwhile negotiating partners to tacitly recognize it as a nuclear-armed nation.
"In the past, the North considered the possibility of giving up nuclear weapons in exchange for assistance," Chinese Central Party School analyst Zhang Liangui said in an interview with the Global Times newspaper. "But now it wants to turn back to the negotiation table as a nuclear state and act as a supervisor of other nuclear states, implying that if it were to give up nuclear weapons, it would want others to do the same first."
Zhang said other participants in the moribund six-nation negotiations -- China, Japan, South Korea, Russia and the United States -- "should also break the North's illusion that one day they will admit its status as a nuclear state," Yonhap reported.