Scholars of American grand strategy assess the broad contours of US foreign policy and offer prescriptions regarding the best way forward. Their focus is on the overarching purpose or ‘vision’ of US global engagement, identifying vital interests and suggesting how they can best be secured by employing the resources available to the nation in ways that accord with foundational values. Some analyses closely parallel the argument here, but at the level of the nation's overarching foreign policy behaviour. For instance, Dueck has described the way America's ‘limited liability’ grand strategy – whereby it pursues ideologically inspired ambitious ends with limited means to avoid costs – has resulted in suboptimal outcomes in terms of influence, prosperity and security. The perspective here has been narrower than this, focused on the application of one specific element of US power: military force. Nevertheless, this book informs those debates insofar as the chief conclusions add weight to realist perspectives that counsel a measure of restraint in US foreign policy, and they raise serious questions for those who would seek to wield force in a habitual fashion, as if it was an unexceptional tool on a par with diplomacy or economic measures.

The application of military force is often seen as unproblematic in some sweeping grand strategic articulations, especially those associated with the pursuit of continued US primacy and liberal interventionism. War, however small-scale or remotely conducted, is a distinctly unpredictable and unwieldy instrument that can easily escape the control of its users and lead them down unintended and perilous paths. Circumspection is vital in this respect. Any decision to employ force is a serious matter, deserving of careful consideration, democratic deliberation and measured strategic assessment. As Clausewitz reminded us, ‘war is no place for irresponsible enthusiasts. It is a serious means to a serious end.’

Given the harmful consequences associated with the practices of delegation, danger-proofing and darkness surveyed in Chapter 7, in some extreme situations, where it is judged that vital American interests are engaged, more robust direct responses may be preferable to the kind of minimalist or outsourced approaches we have discussed. Some analysts lean toward the apparent logical solution of consistently employing overwhelming force, as in essence the earlier Weinberger doctrine recommended.