A U.S. nuclear-powered aircraft carrier arrived in the South Korean port city of Busan on Thursday, in a show of force in response to North Korea's ongoing nuclear and missile threats.The arrival of the U.S. Navy's Ronald Reagan came as the United States, South Korea and Japan held a joint exercise on Monday and Tuesday in international waters southeast of South Korea's Jeju Island.South Korea's Defense Ministry said earlier this week that the five-day visit of the carrier and its strike group comes as part of an agreement made between Seoul and Washington in April to enhance the "regular v…READ FULL ARTICLE