This article explores how states engage in external balancing short of full-fledged alliances, challenging the traditional structural realist view that equates external balancing with alliance formation. It introduces the concept of militarised-cooperative buck-passing to explain flexible, politically non-binding military partnerships that involve targeted defence cooperation without formal or informal commitments to mutual defence. Through a comparative analysis of the US–India and China–Russia military partnerships, the article argues that both dyads exemplify this mode of external balancing. In each case, states strengthen each other’s military capabilities in mutually relevant domains – such as fighter-jet technology and air defences – while mutually delegating the primary responsibility of defending oneself against the threat to the partner. This approach increases the cost of aggression for a common threat without incurring the risks and obligations of formal alliances. The concept of militarised-cooperative buck-passing offers greater analytical clarity than broad categories like ‘alignment’ or ‘strategic partnership’, which fail to specify the mechanisms and implications of such defence cooperation.
Lauro Borges (Tue,) studied this question.