A U.S. soldier checks South Korean soldiers during their decontamination training against possible chemical, biological, radiological and nuclear threats in Yeoncheon

A U.S. soldier checks South Korean soldiers during their decontamination training against possible chemical, biological, radiological and nuclear threats in Yeoncheon

A U.S. soldier (R) checks South Korean soldiers during their decontamination training against possible chemical, biological, radiological and nuclear threats at Steel Zenith Field Training Exercise in Yeoncheon, about 65 km (40 miles) north of Seoul, May 16, 2013. U.S. Troops from the 1st Battalion, 38th Field Artillery Regiment and 23rd Chemical Battalion conducted the military drills on Thursday with South Korean soldiers at a training field near the demilitarised zone separating North Korea from the South. The two Koreas remain technically at war under a mere truce that ended hostilities in their 1950-53 conflict. REUTERS/Lee Jae-Won (SOUTH KOREA - Tags: POLITICS MILITARY) - RTXZOKB

March 20, 2017 3:36 PM (UTC+8)