North Korea 'successfully' test fires submarine-launched missile

North Korea has said that it has successfully test fired a submarine-launched missile, which, if confirmed, could be a significant addition to its nuclear arsenal.
According to analysts, North Korea has several nuclear warheads but the new weapon marks an important advance as submarine-fired devices are difficult to detect, reported the BBC.
The United States termed the use of ballistic missiles a "clear violation" of the United Nations sanctions against North Korea.
A statement issued by the U.S. State Department although made no comment on the reported test but urged North Korea to "refrain from actions that further raise tensions in the region.