Abstract
<title>Abstract</title> <p>How does systemic stress reshape alignment among non-allied major and middle powers? That coalitions such as BRICS cohere in periods of relative calm and diverge selectively under crisis is by now a well-documented regularity; this article does not claim novelty for the observation. Its contribution is an instrument: the Crisis-Adjusted Divergence Index (CADI), which models states as five-dimensional structural exposure vectors — security exposure, defence-industrial dependence, trade concentration, technological dependency and regulatory-financial alignment — and treats systemic stress as a continuous scalar (σ) that dynamically reweights the salience of those dimensions through a softmax function. Unlike established quantitative measures of alignment, which capture revealed preferences after behaviour has occurred, the CADI is a leading indicator of structural pressure conditional on stress. Applied to the Brazil–India, Brazil–China and India–China dyads with σ calibrated on the Geopolitical Risk index, the CADI rises by 86 and 81 per cent for the two structurally heterogeneous dyads between baseline stability and the 2022 peak, while remaining flat for the structurally similar India–China dyad — as the framework’s compatibility hypothesis predicts. External validation against UN General Assembly ideal-point distances yields a pooled within-dyad correlation of 0.56 (0.68 for heterogeneous dyads), and the stress-reweighting mechanism reduces prediction error by 36 per cent relative to a static-distance null. The India–China case delimits the index’s scope — profile similarity is necessary but not sufficient for alignment — and motivates a directional extension. Implications for policymakers in the Global North and Global South are drawn.</p>