evidence: SEOUL, South Korea (AP) — North Korea said Wednesday it will permanently block its border with South Korea and build front-line 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. [...] South Korean officials earlier said North Korea had already been adding anti-tank barriers and reinforcing roads on its side of the border since April in a likely attempt to boost its front-line security posture and prevent its soldiers and citizens from defecting to South Korea. In a report to parliament on Tuesday, South Korea’s Unification Ministry said that North Korea has been removing ties on the northern side of cross-border railways and nearby lamps and planting mines along the border. [...] 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.