South Korean marines ride on the back of a truck on Yeonpyeong Island, South Korea, on Friday, Dec. 10, 2010. South Korean President Lee Myung-bak is pushing the idea of Korean unification, even as tensions remain high two weeks after the North shelled a South Korean island, killing four and setting the region on edge. (AP Photo/Yonhap, Kim Ju-sung)

Photo by: Kim Ju-sung

South Korean marines ride on the back of a truck on Yeonpyeong Island, South Korea, on Friday, Dec. 10, 2010. South Korean President Lee Myung-bak is pushing the idea of Korean unification, even as tensions remain high two weeks after the North shelled a South Korean island, killing four and setting the region on edge. (AP Photo/Yonhap, Kim Ju-sung)