Description:It's cold, but the soldiers are performing their duties. South Korean troops conducted river-crossing exercises, which North Korea has strongly denounced. About 1,000 soldiers were mobilised during the day-long training in the winter weather. South Korea has held joint military exercises with the U.S. before, which also drew strong opposition from the North. There are about 30,000 U.S. troops stationed in South Korea to support the country's 670,000 troops.(1:04)