Strategic competition, or great power competition, has become a new buzz-word in international politics. Yet, few studies have undertaken any systematic examination of what caused its return to the centre stage of international relations. This study hence formulates a parsimonious structural explanation of renewed great power rivalry. Relying on the insights of neorealism and its two structural variants—defensive realism and offensive realism—the study first suggests that current definitions of strategic competition are, due to their emphasis on power competition, overly imbued with offensive realist nuances. However, security competition, which originates in the security dilemma, also underlies strategic competition. Employing neorealism’s polarity perspective, this study then posits that the end of US-led unipolarity and ongoing power deconcentration in the international system are major causes of renewed great power rivalry. While unipolarity harnesses the anarchic effect and compels second-tier major powers to exercise strategic restraint, multipolarity resurrects insecurity and removes disincentives for the aggressive pursuit of power, influence, and status. Ever intensifying security competition and power competition have thus shifted international politics into a new paradigm defined by great power conflict.