Examines military cooperation between the US and its allies, demonstrating that demands cannot always be met by democratic allies due to domestic political constraints, and that concerns over military assets can further limit governments' ability to commit resources. Analyzes responses to the wars in Afghanistan and Iraq by the UK, Canada, and Australia.

Introduction : why are allies so unpredictable? -- A theory of asymmetric security cooperation -- Exceeding expectations : the UK and the War on Terror -- Canada-US relations and the War on Terror -- Australia : regional power, global war -- Conclusion : overcoming the great asymmetry.