SEOUL, South Korea — The Defense Ministry of South Korea said Tuesday that North Korea appeared to have made a “significant” advance toward making a nuclear warhead small enough to fit onto a long-range missile capable of reaching the West Coast of the United States. The ministry, which included the assessment in its latest white paper, also suggested that the North now had a missile that could fly that far.
Ministry officials stressed that North Korea had yet to conduct a test to demonstrate an ability to deliver a nuclear warhead by missile at such a long distance. The white paper also did not elaborate on how South Korean officials had reached their conclusions, except for noting the North’s success in putting a satellite into orbit on a long-range rocket in 2012 and its third underground nuclear test in February 2013.
The South’s assessments, if correct, could change calculations about the vulnerability of the United States.
American officials have struggled for years to figure out how close North Korea has come to building a nuclear-tipped intercontinental ballistic missile and have sometimes issued conflicting conclusions. In early 2011, Robert M. Gates, who was the defense secretary, said that North Korea was within five years of being able to strike the continental United States with an intercontinental ballistic missile.
In April 2013, the United States Defense Intelligence Agency said that it had “moderate confidence” that North Korea had mastered the technology of building a miniaturized weapon to fit atop a missile. Within days, however, President Obama said he did not believe that the North had that capability….