Historically associated with transatlantic discords about Atlantic alliance, burden-sharing is a term that comes and goes on policy agenda.1 Last year, Robert Gates made headlines when he chastised most of his European counterparts for not shouldering enough of burden in NATO -led operation in Libya. Evoking spectre of a two-tiered made up of those willing and able to pay price and bear burdens of alliance commitments, and those who enjoy benefits of NATO membership... but don't want to share risks and costs, outgoing US defence secretary warned, [t]he blunt reality is that there will be dwindling appetite and patience in US congress - and in American body politic writ large - to expend increasingly precious funds on behalf of nations that are apparently unwilling to devote necessary resources or make necessary changes to be serious and capable partners in their own defense.2 A few months earlier, Gates had made similar comments, this time about what he saw as Europeans' over-eagerness to pull out of Afghanistan, where their troops make up less than a third of total forces deployed. In a way, Gates had a point. In last io years, US's share of total NATO spending has indeed jumped from 50 percent to 75 percent, in no small part because of America's own formidable increase in military expenditures after 11 September 2001.Accusations of free-riding have marred transatlantic relations ever since creation of Atlantic alliance in 1949. Then as now, rhetoric of burden- sharing has served as a useful rhetorical weapon to blame those who were seen as not contributing enough to cause. Each time, however, Washington's call has fallen on deaf ears, at least in public. In private, European and Canadian officials highlight other contributions they they are to NATO operations, for example in shape of development aid or considerable troop casualties in Afghanistan. They mention UN peacekeeping missions, such as in Lebanon, where US is not involved. Cynics admit that they never really bought much into military adventures into which US threw them, and that US itself did not seem to believe much in Libya mission. The reality, French foreign minister Alain Juppe retorted to Gates, is that it is Europeans who think Americans aren't enough.3The evolution of transatlantic debate suggests two things. First, burden-sharing is about more than NATO. One cannot just look at defence spending at a time when humanitarian aid, diplomatic mediation, and fight against climate change can all be considered contributions of a sort to collective security.4 Disentangling what counts as a contribution to which public good is no easy thing. Second, burden-sharing is a contested political concept. Statesmen and diplomats do not speak abstract language of public choice, with its non-excludable and non-rival goods. Rather, they talk about being fair, doing what you can, and making a real contribution. In other words, they speak normative language of justice rather than utilitarian language of economics.Rather than attempting to prove who's right and who's wrong, our research agenda is to reconstruct practical logic of claims that bedevil global governance. Our starting point is that we have to understand logic of burden- sharing a lot better before we start pointing fingers at other countries and congratulating our own. In our ongoing project, we look at how government elites construe good of collective security, different contribution strategies that they develop, and domestic and international constraints and opportunities that they face in implementing such strategies. We address each of these issues in turn.WHAT IS GOOD?The first question that comes to mind is how to define the In a broad sense, international security is assumed to be a collective good. …