North Korea is blocking entry of South Korean workers into a joint industrial zone just north of the border, jeopardizing the last remaining sign of cooperation between the two foes.
South Korean vehicles turn back after being refused entry to Kaesong, North Korea, April 3, 2013.
Anti-war protesters raise signs during a rally denouncing the joint military drills between the South Korea and the United States near the U.S. Embassy in Seoul, South Korea, April 3, 2013.
North Koreans attend a rally against the United States and South Korea in Nampo, North Korea, April 3, 2013.
South Korean soldiers wearing gas masks gather during their military exercise in the border city of Paju, north of Seoul, South Korea, April 2, 2013.
South Korean soldiers conduct field firing drills near the demilitarized zone separating the two Koreas in Paju, north of Seoul, April 2, 2013.
South Korean Army armored vehicles cross a pontoon bridge during an exercise against possible attacks by North Korea near the demilitarized zone in Hwacheon, South Korea, April 1, 2013.
North Korean women walk in front of portraits of North Korea's founder Kim Il-sung (L) and late leader Kim Jong-il at Kim Il-sung Square in Pyongyang, in this photo provided by Kyodo, April 1, 2013.
North Korean leader Kim Jong Un presides over a plenary meeting of the Central Committee of the Workers' Party of Korea in Pyongyang March 31, 2013 in this picture released by the North's official KCNA news agency.
A U.S. Air Force B-2 stealth bomber flies near Osan U.S. Air Base in Pyeongtaek, south of Seoul, South Korea, March 28, 2013.
South Korean vehicles return from a joint industrial complex at the North Korean city of Kaesong as a U.S. Army soldier watches at the customs, immigration and quarantine office, near the Demilitarized Zone, March 28, 2013.
Soldiers of the Korean People's Army take part in landing and anti-landing drills in the eastern sector of the front and the east coastal area, North Korea, March 25, 2013.