NEW : Beijing is `` likely to try to calm things down , '' Sweden 's foreign minister says . South takes `` seriously '' north 's threat to jeopardize joint Kaesong economic zone . North Korea has threatened a nuclear strike on Seoul and Washington if the United States continues deploying an advanced missile defense system in South Korea. James Hardy , Asia-Pacific editor of IHS Jane 's Defense Weekly , wrote in an opinion column published Thursday on CNN.com . North Korea threatens `` all-out war and nuclear war '' on its enemies , state news reports .
NEW : Beijing is `` likely to try to calm things down , '' Sweden 's foreign minister says . South takes `` seriously '' north 's threat to jeopardize joint Kaesong economic zone . North Korea has threatened a nuclear strike on Seoul and Washington if the United States continues deploying an advanced missile defense system in South Korea. North Korea threatens `` all-out war and nuclear war '' on its enemies , state news reports .