This article contributes to a growing literature that questions the traditional ‘politics stops at the water’s edge’ paradigm. Left- and right-wing parties hold diverging ideologies and articulate specific party programmes regarding policy priorities in the realm of foreign and security affairs. The impact of partisan contestations over foreign policy priorities can be traced in defence and foreign aid spending. We understand this ‘bomb-or-build’-balance as two sides of a coin which shapes the international posture of democracies. Our quantitative analysis of 21 OECD countries (1988–2014) reveals that the ideological positions of the parties in government influence the relative importance of military expenditures versus foreign aid. The more the ideological position of a government is tilted towards the military (and against internationalism), the more the ‘bomb-or-build’-balance shifts in favour of military spending (and in disfavour of foreign aid).

This article contributes to a burgeoning literature on parliamentary war powers by investigating the case of the US Congress drawing on both International Relations (IR) research and traditional war powers studies. Applying a fuzzy-set qualitative comparative analysis and case study method, we examine the conditions shaping congressional assertiveness. The article shows that the lack of national security interests and divided government are important conditions for members of Congress to criticize presidential intervention policies. While previous US war powers studies focused on the influence of partisanship, this article holds that domestic as well as international factors influence congressional behavior. A short comparative case study of two US military interventions (Libya 2011, ISIS 2014–15) during the Obama presidency serves to illustrate the findings.

This article examines the extent and patterns of politicisation in the field of military interventions for the USA after the end of the Cold War. The analysis shows that key votes on war and peace in the US Congress are contested to a higher degree than in the European parliaments. It finds that Republican members of Congress (MoC) are in general more supportive of military interventions than Democrats. At the same time, party loyalty towards the president influences the level of support. Furthermore, an original content analysis of congressional debates reveals that MoC use specific argumentative frames in line with partisan ideology. Both parts of the analysis point to the relevance of partisanship and partisan ideology for understanding the politicisation of military interventions policies. Thus, the traditional bipartisan spirit, paradigmatically invoked by US Senator Arthur Vandenberg during the Cold War, has almost vanished.

US arms control policies have shifted frequently in the last 60 years, ranging from the role of a ‘brakeman’ regarding international arms control, to the role of a ‘booster,’ initiating new agreements. My article analyzes the conditions that contribute to this mixed pattern. A crisp-set Qualitative Comparative Analysis (QCA) evaluates 24 cases of US decisions on international arms control treaties (1963–2021). The analysis reveals that the strength of conservative treaty skeptics in the Senate, in conjunction with other factors, has contributed to the demise of arms control policies since the end of the Cold War. A brief study of the Trump administration’s arms control policies provides case-sensitive insights to corroborate the conditions identified by the QCA. The findings suggest that conservative treaty skeptics contested the bipartisan consensus and thus impaired the ability of the USA to perform its leadership role within the international arms control regime.

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