Condemns North Korea's development of multiple intercontinental ballistic missiles. Welcomes the deployment of the Terminal High Altitude Area Defense (THAAD) system in South Korea to counter North Korea's missile threat. Urges the government of the People's Republic of China to immediately cease its diplomatic intimidation and economic coercion against South Korea in an attempt to block the THAAD deployment. Reaffirms: (1) U.S. support for a layered, integrated, multi-tier missile defense system to protect Americans and allies in Northeast Asia; and (2) the U.S. commitment to its alliances and to trilateral cooperation with South Korea and Japan. Expresses support for: (1) continued U.S.-South Korea bilateral security cooperation and the consideration of additional measures to strengthen the alliance, including expanded foreign military sales and joint exercises; and (2) the intelligence sharing agreement between Japan and South Korea signed on November 23, 2016, concerning the direct exchange of intelligence on North Korean threats, and urges its full implementation. Calls upon: (1) China to use its considerable leverage to pressure North Korean leaders to cease their provocative behavior, abandon and dismantle their nuclear and missile programs, and comply with all relevant United Nations Security Council Resolutions; (2) the United States to fully enforce all existing economic sanctions on North Korea and to seek to continuously adapt the sanctions regime to address evasive techniques employed by such regime; and (3) the Department of State to undertake a comprehensive and rigorous diplomatic effort to urge allies and other countries to fully enforce, and build upon, existing international sanctions on North Korea.