**FILE** President Obama listens to a question during a news conference with South Korean President Park Geun-Hye in the East Room of the White House on May 7, 2013. (Associated Press)
South Korean President Park Geun-Hye speaks during a news conference with President Obama in the East Room of the White House in Washington on Tuesday, May 7, 2013. (AP Photo/Jacquelyn Martin)
South Korean President Park Geun-hye, left, shakes hands with Microsoft founder Bill Gates before their meeting at the presidential Blue House in Seoul, South Korea, Monday, April 22, 2013. (AP Photo/Lee Jin-man, Pool)
A North Korean soldier looks toward South Korea through a pair of binoculars at the border village of Panmunjom in the Demilitarized Zone, which has separated the two Koreas since the Korean War, on Tuesday, April 23, 2013. (AP Photo/Lee Jin-man)
South Korean Army soldiers patrol on Unification Bridge in Paju, South Korea, near the border village of Panmunjom, on April 16, 2013. North Korea's state media said the Supreme Command of the Korean People's Army issued an ultimatum demanding an apology from South Korea for "hostile acts" and threatening that unspecified retaliatory actions would happen at any time. (Associated Press)
South Korean Army soldiers patrol on Unification Bridge in Paju, South Korea, near the border village of Panmunjom, Tuesday, April 16, 2013. North Korea's state media said Tuesday the Supreme Command of the Korean People's Army issued an ultimatum demanding an apology from South Korea for "hostile acts" and threatening that unspecified retaliatory actions would happen at any time. (AP Photo/Ahn Young-joon)
Visitors use binoculars to scan North Korean territory from the vantage point of the unification observation post near the border village of Panmunjom separating North and South Korea. (Associated Press)