The United States and South Korea have had a long-standing alliance since 1950, and the two nations continue to cooperate to battle global threats and to boost economic growth. Under the U.S.-R.O.K. Mutual Defense Treaty, the United States maintains military forces in South Korea to help the country defend itself. The nations also collaborate on the nuclear threat of North Korea and on the denuclearization of Korea as a whole. Then, in 2012, the Korea-U.S. Free Trade Agreement was established. The United States is now South Korea’s largest trading partner after China, and South Korea is the seventh largest trading partner of the United States. Recently, however, the relationship between the two countries have become strained due to the change of political leaders in both countries in 2017. The foundation of the U.S.-R.O.K military alliance will likely persist, although, a diplomatic or military disturbance could alter some security arrangements.