Attack warning sirens are seen near a guard post overlooking the Yellow Sea on Baengnyeong Island, South Korea on April 18, 2012. When an armistice ended open conflict on the Korean peninsula in 1953, there was no agreed upon boundary set up in the Yellow Sea between the two Koreas. Each side has drawn their own line, the South Korean controlled islands of Yeonpyeong, Baengnyeong and Daecheong are located between the two disputed lines.