Since the end of World War II, Australia has enjoyed an ideologically simple security environment: all its core allies have been liberal democracies, and all its foes have been illiberal. The United States, the architect and defender of the liberal rules-based world order, has long served as Australia’s most important security guarantor against illiberal foes. But this simple division of the world into liberal allies and illiberal foes has ended, at least for now and perhaps for good.