SEOUL -- A U.S. nuclear-powered submarine arrived at a key naval base in the southeastern city of Busan on Tuesday to replenish supplies and provide rest for crew members, South Korea's Navy said.The USS Greeneville, a Los Angeles-class attack submarine, entered the naval base in Busan, some 330 kilometers southeast of Seoul, earlier in the day, the Navy said."The Navy plans to boost exchanges and cooperation between the navies of South Korea and the United States and strengthen our combined defense posture on the occasion of the USS Greeneville's entry," it said.The USS Greeneville last v…READ FULL ARTICLE