Since February 2022, Ukraine has been defending itself against yet another Russian war of aggression. Now that immediate support - military, diplomatic, financial and humanitarian - for Ukraine has improved, the country’s long-term security needs to be addressed. Looking ahead, security...

We investigate the role of networks of military alliances in preventing or encouraging wars between groups of countries. A country is vulnerable to attack if there is some fully-allied group of countries that can defeat that country and its (remaining) allies based on a function of their...