The estimate by the ministry based on information from debris retrieved in waters off South Korea's west coast suggests the rocket has enough range to reach the US west coast while mounted with a nuclear weapon weighing 500 to 600 kilograms, the sources said.
Until now, experts were split on the payload capability of the rocket, launched on December 12 and believed to have carried a roughly 100-kg object into space.
The sources said it remains unclear if North Korea possesses technology to make a warhead which can withstand the impact and heat during reentry into the atmosphere.
The object recovered by the ministry measures about 7.5 metres long with a diameter of 2.4 metres and weighs 3.2 tons.
Analysis of the object revealed it to be capable of carrying some 48 tons of oxidising agent used in rocket fuel, the sources said.
The oxidising agent in the rocket was found to be red fuming nitric acid, widely seen in Soviet-era ballistic missiles, not liquid oxygen typically used as rocket propellant for a satellite launch, strongly suggesting Pyongyang's development of an intercontinental ballistic missile, they said. (Kyodo)
Seoul: North Korea's recently launched rocket is capable of propelling a rudimentary nuclear warhead more than 10,000 kilometres, far enough to reach the US mainland, according to South Korean Defense Ministry sources.
First Published: Sunday, December 23, 2012, 15:19