evidence: SEOUL, South Korea — North Korea said Wednesday it will permanently block its border with South Korea and build frontline defense structures to cope with "confrontational hysteria" by South Korean and U.S. forces, while not announcing an expected constitutional revision to formally designate South Korea its principal enemy and codify new national borders. [...] At the center of outside attention was whether North Korea makes new legal claims on the waters currently controlled by South Korea off their west coast. The poorly marked western sea boundary is where three bloody naval skirmishes and two deadly attacks blamed on North Korea happened in the past 25 years.