The paper introduces a welfarist approach to the national safety of a nation with membership in a defense alliance as … insurance devices, the domestic military budget and the incremental safety provided by the membership in the alliance. The … commitment of the alliance in the creation of safety is, however, imperfect. A sufficient condition is stated for the non …

internal fight reduces the alliance's ability to succeed against the outside enemy. Second, the option to make non …-binding declarations on non-aggression in the relationship between alliance members does not make peaceful settlement within the alliance … more likely. Third, higher differences in the alliance players' contributions to alliance effort lead to more internal …

uniformly selected to initiate an alliance and to invite collaboration partners. These decide about acceptance based on an … individual threshold that is compared with the utility expected from joining the current alliance. The benefit of alliances … cost of an alliance reflects its coordination effort. Two free parameters ac and a1 scale the costs and the individual …