North Korea says it is restarting operations at a shuttered plutonium nuclear reactor and hinted at further enrichment of uranium, adding to already heightened tensions on the Korean peninsula.
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.
University students punch the air as they march through Kim Il Sung Square in downtown Pyongyang, North Korea, March 29, 2013.
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.
A man walks past propaganda posters that threaten punishment to the "U.S. imperialists and their allies," Pyongyang, North Korea, March 26, 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.