Nuclear security

North Korea's Kim calls for expansion of nuclear arsenal

North Korean leader Kim Jong Un called for an expansion of the size and power of his country's nuclear arsenal, state media said on Wednesday, a week after a nuclear test that drew condemnation from its neighbors and the United States.

Last week's nuclear test was North Korea's fourth, although the United States and experts doubt the North's claim that it was of a more powerful hydrogen bomb, as the blast was of about the same size as that from an atomic bomb test in 2013.

"(Kim) called for bolstering up both in quality and quantity the nuclear force capable of making nuclear strikes at the U.S.-led imperialists any time and in any space ... if they encroach upon the sovereignty of the DPRK and make threatening provocations," the official KCNA state news agency said.