A South Korean soldier uses binoculars as he looks across to the north side of the border at the Imjingak pavilion near the demilitarized zone (DMZ) in Paju, South Korea, on Wednesday, April 3, 2013. North Korea prevented South Korean workers from entering a jointly run industrial park today, adding to tensions after saying it will restart a mothballed nuclear plant and threatening to attack its southern neighbor. Photographer: SeongJoon Cho/Bloomberg via Getty Images