Power vs. threat: Explanations of United States balancing against the Soviet Union after 1976

Balance of power ("power") and balance of threat ("threat") provide competing, but related, explanations of balancing. Which better explains balancing? Power in conditions of bipolarity expects that the two powers will engage in balancing that will produce a balance in which each is capable of a defending its vital interests. A change in the military capability of one sufficient to affect the ability of the other to defend its interests with good prospects for success will cause balancing by the other. Threat differs in its expectation that a great power with military capability at least sufficient for a high-confidence defense in all contested theaters will balance if it perceives that the other country has aggressive intentions, defined as a high propensity to attempt to compel it that may involve initiation of war for gain or acceptance of the risk that initiation of compellence may lead to war. Fearing its military capability is insufficient to dissuade such a country, it increases its military capability.; Three observable implications allow a test of power and threat as explanations of US balancing in the late-1970s: sufficiency of US general purpose and strategic forces, US wartime prospects, and US assessments of Soviet intentions. The increasing insufficiency of US military capability and perceptions that the US did not have good wartime prospects means that increases in US capability are readily explained by power. It also means that the condition of threat that the US had sufficient military capability in all contested theaters is not satisfied and threat's additional element of aggressive intentions is not required. Finally, there was not a dominant perception among US leaders that the Soviet Union was attempting to compel the US so a critical positive expectation of threat is not satisfied. I conclude that power provides the better explanation. I address Walt's argument that the US was more powerful than the Soviet Union and three appendices consider economic elements of power and military expenditures.