The United States stands amid a strategic discontinuity – a period when unpredictable, unforeseen, and rapid changes occur that confound or disrupt previous expectations or estimates. A sudden shift in the external environment challenging status quo world order produces a discontinuity, as does a sudden transition in U.S. domestic interests or public will. Currently, rising powers and non-state actors challenge U.S. hegemony militarily and economically. Domestic fiscal uncertainty threatens critical funding sources for development and execution of the national instruments of power. Two discontinuities in U.S. history surface for their similarity to today’s environment – the post-Vietnam era and the post-Cold War timeframe. Following the Vietnam War, dramatic change occurred, but the U.S. assessed the new strategic environment and ultimately achieved new, prioritized goals. Short of such assessment after the Cold War, the U.S. failed to identify significant changes in the strategic environment, leading to major missteps later. U.S. leadership can apply lessons from these events to determine the best approach for managing the current discontinuity.