Welcomes: (1) the President of the Republic of Korea, Moon Jae-in, on his first official visit to the United States; and (2) opportunities to strengthen security consultation, cooperation, and partnership on matters such as space, cyber, and missile defense. Reaffirms the importance of: (1) the U.S.-South Korea alliance, as enshrined in the Mutual Defense Treaty of 1953; and (2) the U.S. commitment to defend South Korea under Article III of that treaty. Reinforces U.S. commitments to provide extended deterrence to South Korea. Supports efforts to: (1) strengthen such alliance and defend it against provocations by North Korea, (2) protect U.S. Armed Forces stationed on the Korean Peninsula, and (3) peacefully achieve a Korean Peninsula free of nuclear weapons through a diplomatic process. Urges the United States and South Korea to work together: (1) with members of the United Nations Security Council and other member states, to enforce existing sanctions and consider the need to pass additional new measures under Article 41 of the United Nations Charter; and (2) to implement all aspects of the U.S.-Republic of Korea Free Trade Agreement. Encourages the U.S. and South Korean governments to continue to broaden and deepen the alliance by enhancing cooperation and building new partnerships in the security, economic, energy, scientific, health, education, and cultural spheres.