North Korea threatens to fire at S. Korea, U.S. 27 Feb 2011 North Korea threatened Sunday to enlarge its nuclear arsenal and mercilessly attack South Korea and the United States, as the allies prepared to start annual joint military drills which the North says are a rehearsal for an invasion. North Korea called the planned South Korea-U.S. drills a "dangerous military scheme." Earlier Sunday, the North's military warned that it would destroy South Korean border towns if Seoul continues to allow activists to launch propaganda leaflets toward the country.