SEOUL • North Korea now has enough plutonium to make 10 nuclear bombs, South Korea said yesterday, a week after leader Kim Jong Un said Pyongyang was close to test-launching an intercontinental ballistic missile (ICBM).
The isolated communist state, which has carried out five nuclear tests and numerous missile launches, is thought to be planning a nu- clear push this year as it seeks to develop a weapons system capable of hitting the United States mainland.
The US might monitor the North's ICBM test and gather intelligence rather than destroy the missile, as long as the launch did not pose a threat, Defence Secretary Ash Carter said on Tuesday.
"If the missile is threatening, it will be intercepted. If it's not threatening, we won't necessarily do so," he added in his final news briefing before President Barack Obama leaves office on Jan 20.
"Because it may be more to our advantage to, first of all, save our interceptor inventory and, second, to gather intelligence from the flight, rather than do that (intercept the ICBM), when it's not threatening."
The top US military officer, Marine General Joseph Dunford, who will stay in his role as chairman of the Joint Chiefs of Staff, concurred with Mr Carter at the event but did not enter into specifics.
Analysts are divided over how close Pyongyang is to realising its full nuclear ambitions but all agree it has made enormous strides since Mr Kim took over as leader from his father Kim Jong Il, who died in December 2011.
Mr Carter's language left open the possibility of US military action in any scenario.
Analysts are divided over how close Pyongyang is to realising its full nuclear ambitions but all agree that it has made enormous strides since Mr Kim took over as leader from his father Kim Jong Il, who died in December 2011.
Seoul's defence ministry said the North is believed to have some 50kg of weapons-grade plutonium as of the end of last year - enough to make about 10 weapons - up from 40kg eight years earlier.
The North also has a "considerable" ability to produce weapons based on highly enriched uranium, it said in a two-yearly White Paper.
But it did not estimate weapons-grade uranium stocks, citing impenetrable secrecy in the North's uranium programme.
The Institute for Science and International Security, a US think- tank, estimated in June that the North's total nuclear arsenal was more than 21 bombs, up from 10 to 16 weapons in 2014, based on estimates of plutonium and uranium.
The North has boosted pluto- nium supplies by reactivating its once-mothballed nuclear reactor in Yongbyon, the South's defence ministry said.
North Korea deactivated the Yongbyon reactor in 2007 under an aid-for-disarmament accord but began renovating it after Pyongyang's third nuclear test in 2013.
The type of plutonium suitable for a nuclear bomb typically needs to be extracted from spent nuclear reactor fuel.
Mr Kim said in a New Year's speech that Pyongyang was in the "final stages" of developing an ICBM of the kind that could threaten US territory.
The address drew a swift response from US President-elect Donald Trump, who took to Twitter vowing to halt Pyongyang in its tracks.
However, preventing an ICBM test is far easier said than done, and Mr Trump has given no indication of how he might roll back the North's weapons programmes after he takes office, something successive US administrations, both Democratic and Republican, had failed to do.
An assessment from last year, released by the Pentagon's weapons testing office on Tuesday, said that American ground-based interceptors - meant to knock out any incoming ICBMs - still had low reliability, giving the system itself a limited capability of shielding the country.
AGENCE FRANCE-PRESSE, REUTERS