U.S. Army helicopters carrying South Korean army soldiers take off during a South Korea-U.S. combined air assault exercise in Yeoju, southeast of Seoul, December 8, 2009. U.S. President Barack Obama's first envoy to North Korea arrived in Pyongyang on Tuesday to try to coax the prickly state back to the nuclear talks it quit a year ago, but without offering it any new incentives. REUTERS/Lee Jae-Won (SOUTH KOREA MILITARY POLITICS)