How the United States addresses direct threats to its core or vital interests over time is the essence of grand strategy. Typically, America’s solutions are not new, although the technologies employed often are. The first principle is to meet the threat as far from the homeland as possible. Thus, since the end of World War II, the United States has established bases, positioned forces, and stockpiled weapons and munitions around the globe, buttressed by economic and development assistance, exercises, formal treaties, coalitions of the willing, and alliances. (Counterproliferation may also be seen in this light.) While U.S. ground forces have largely come home, and key installations such as Torrejon Air Base in Spain and Clark Air Base and Naval Base Subic Bay in the Philippines were closed after the Cold War, America’s network of overseas bases, airfields, and alliances as well as forward-deployed air and naval forces is still extensive. America’s ability to project power globally and sustain its forces almost indefinitely remains unmatched. U.S. satellites survey the globe and monitor adversary communications continuously. Though smaller than during the Cold War, the U.S. strategic nuclear arsenal is survivable, redundant, and accurate, providing an absolute nuclear deterrent against any adversary. Next, the United States prefers to meet serious threats using different tools at once, relying on intelligence, diplomacy, forward presence, and economic power to forestall, deflect, or defuse security challenges and reserving military force as a last resort. Still, U.S. military power is awesome. Its strength across the warfighting domains, supported by an unmatched ability to project and sustain military forces far from the homeland, remains far ahead of the rest of the world. Whenever possible, the United States will address threats in tandem with allies, partners, or likeminded states, working through international organizations like the UN or NATO and conducting preconflict engagement and “shaping” operations on a large scale. Yet when vital interests are at stake, the United States will act unilaterally if necessary. Preemption to disrupt or prevent imminent threats falls well within America’s grand strategic calculus. Prevention—the use of force to defeat threats before they become imminent—has, on the other hand, far less provenance.