Hydrogen bomb test self-defensive step: Kim Jong Un

North Korean leader Kim Jong Un has said that the country conducted a hydrogen bomb test as a self-defensive step against a US threat of nuclear war and had a sovereign right to do so without being criticised.

Kim's comments were in line with the North's official rhetoric blaming the United States for deploying nuclear weapons on the Korean peninsula to justify its nuclear programme but were the first by its leader since Wednesday's blast.  The United States has said it has no nuclear weapons stationed in South Korea. But it has been in discussion with the South Korea about deploying strategic weapons after the test.  Meanwhile, a powerful US B-52 bomber flew over South Korea amid standoff.  North Korea's fourth nuclear test on Wednesday angered both the United States and China, although the US government and weapons experts doubt the North's claim that the device it set off was a hydrogen bomb.  Experts believe the test was designed to set the stage for a rare general meeting of its ruling Workers' Party, the first since 1980.