SEOUL - North Korea has probably succeeded in miniaturizing a nuclear device, South Korea's defense minister said on Monday, an advance that would in theory allow the hermit state to place an atomic warhead on a rocket.
Regional powers have for years tried -- with a mix of aid offers and punitive sanctions -- in vain to stop Pyongyang pressing ahead with a nuclear weapons program it argues is a necessary defense against a hostile United States and South Korea with which it still has no peace treaty to formally end the 1950-53 Korean War.
Kim Kwan-jin offered no evidence to back his assertion but said the North had had enough time for such a development.
"It has been quite a while, enough time for them to have succeeded in miniaturization," he told a parliamentary defense committee.
If true, it would mark a key advance in the North's drive to develop a functioning nuclear weapon though that threat appears to be potential rather than actual.
It detonated nuclear devices in 2006 and 2009 but neither was considered by weapons experts to have been successful, though they say the impoverished state has enough fissile material for up to 10 nuclear weapons.
It is believed to be preparing a third test at a test site on its east coast.
The North has also been working, so far with little success, to build a missile capable of delivering a nuclear weapon across the Pacific, as far as the United States.
Talks with major powers on its nuclear weapons program have been on ice for more than two years though the North has signaled it wants them to resume.
However, both the United States and key allies South Korea and Japan have been reluctant to head back into negotiations which in the past have rewarded the North for little if anything in return.