8/ The book also probes the external validity of the theory via short case studies.

7/ I test the argument via two extensive case studies: Fascist Italy in Spain (1936) and Russia in the Donbas (2014). Dividing the conflicts into several escalation decisions provides significant support for the theory.

6/ For sponsors who DO escalate assistance, then the question is: when do they become active warring parties themselves? Two variables - proxy effectiveness and the costs of delaying battlefield action - determine the sponsor's decision.

5/ Not all sponsors will decide to "escalate" assistance: some will decide to reduce or end support, or will change to other strategies such as mediation and conflict resolution.

4/ Why would sponsors want to change the form of assistance it provides to a warring party? A key reason in the evolution of battlefield dynamics and the balance of power:

3/ We have large literatures on proxy warfare and on military intervention, but much less work on the transition between the two. The book defines first what direct and indirect support are:

2/ The book asks the following question: 𝗪𝗵𝘆 𝗱𝗼 𝘀𝘁𝗮𝘁𝗲𝘀 𝘁𝗵𝗮𝘁 𝗮𝗿𝗲 𝗮𝗹𝗿𝗲𝗮𝗱𝘆 𝘀𝘂𝗽𝗽𝗼𝗿𝘁𝗶𝗻𝗴 𝗮 𝗽𝗮𝗿𝘁𝘆 𝗶𝗻 𝗮 𝗰𝗶𝘃𝗶𝗹 𝘄𝗮𝗿 𝘀𝗼𝗺𝗲𝘁𝗶𝗺𝗲𝘀 𝗱𝗲𝗰𝗶𝗱𝗲 𝘁𝗼 𝗶𝗻𝘁𝗲𝗿𝘃𝗲𝗻𝗲 𝗱𝗶𝗿𝗲𝗰𝘁𝗹𝘆 𝘄𝗶𝘁𝗵 𝘁𝗵𝗲𝗶𝗿 𝗼𝘄𝗻 𝗳𝗼𝗿𝗰𝗲𝘀?

The 🇺🇲🇩🇰🇬🇱 deal is an example of how Europe reduced a transatlantic confrontation: deterrence early in the year and negotiations for future cooperation later. More ideas for keeping transatlantic relations working in my latest brief @euiss.bsky.social:

6/ Europe therefore needs more arrows 🏹 in its quiver: preserve cooperation where possible, but build a stronger capacity to counter coercion—by maintaining European unity, strengthening deterrence and raising the costs of hostile measures.

5/ Europe's dilemma will not change either: it needs to keep cooperation w. DC to avoid opening gaps in deterrence, but it also must be ready to push back against coercion - repeating the successful deterrence of threats over Greenland, but in potentially harder contexts.