North Korean leader Kim Jong Un visits the Turf Institute of the Bioengineering Branch under the State Academy of Sciences in Pyongyang. (KCNA)
North Korean leader Kim Jong Un visits a construction site of the North Korean army, May 7, 2013. (KCNA)
South Korean protesters wear masks of U.S. President Barack Obama and South Korean President Park Geun-hye during a rally denouncing their policy toward North Korea near the U.S. Embassy in Seoul, May 6, 2013.
South Korean vehicles returning from North Korea's Kaesong arrive at the customs, immigration and quarantine office near the border village of Panmunjom, in Paju, South Korea, April 30, 2013.