The People’s Republic of China has clearly stated the importance of resolving the Taiwan question and realizing China’s complete “reunification” to end their century of humiliation. As China grows as the most significant strategic competitor to the United States and develops the military capability to force the issue, understanding what legal authorities the President may exercise in ordering a response is increasingly urgent. This article reviews the legal authorities for the use of force by the United States and examines the contours of the President’s authorities and where they intersect with Congress’s authorities. Through various hypothetical scenarios involving attempts by China to force reunification through other than peaceful means, this article assesses what limits, if any, exist on the President’s authority to order the use of force. In answering this question and identifying whether additional authorities are needed, the article evaluates various legislative proposals currently pending in Congress to determine their impact. Based on this review, it appears the President currently possesses sufficient authority to defend U.S. interests in the Western Pacific, including the defense of Taiwan. While congressional action may not be legally necessary, leaders in the executive and legislative branches should consider whether such action may be beneficial as a policy matter.