The US will try to defend it inevitably – decline causes war

The finding that U.S. entanglement is rare has important implications for international relations scholarship and U.S. foreign policy. For scholars, it casts doubt on classic theories of imperial overstretch in which great powers exhaust their resources by accumulating allies that free ride on their protection and embroil them in military quagmires.22 The U.S. experience instead suggests that great powers can dictate the terms of their security commitments and that allies often help their great power protectors avoid strategic overextension.

For policy, the rarity of U.S. entanglement suggests that the United States’ current grand strategy of deep engagement, which is centered on a network of standing alliances, does not preclude, and may even facilitate, U.S. military restraint. Since 1945 the United States has been, by some measures, the most militarily active state in the world. The most egregious cases of U.S. overreach, however, have stemmed not from entangling alliances, but from the penchant of American leaders to define national interests expansively, to overestimate the magnitude of foreign threats, and to underestimate the costs of military intervention. Scrapping alliances will not correct these bad habits. In fact, disengaging from alliances may unleash the United States to intervene recklessly abroad while leaving it without partners to share the burden when those interventions go awry.