When the shield cracks, every market trembles

Politico reports that NATO Secretary-General Mark Rutte is navigating a summit overshadowed by the question of American commitment — a question the Trump administration has kept deliberately open by floating the idea of withdrawal. I have no recollection of the summit's outcome, and I will not pretend otherwise. But the institutional question it raises is one I spent considerable effort on: what public goods must a sovereign provide before markets can function honestly at all?

The answer I gave in The Wealth of Nations was blunt. Defense comes first. Not because soldiers are more admirable than merchants — they are not, necessarily — but because the merchant's warehouse, the shipper's vessel, and the farmer's field are all forfeit the moment the rule of force replaces the rule of law. Every gain from the division of labor, every benefit of free exchange, presupposes that someone is keeping the peace. The invisible hand requires, at minimum, that no visible fist be allowed to seize the pins from the pin factory.

Now consider the logic of collective defense in the same light I applied to infrastructure and education: it is a public good, meaning that one nation's security within an alliance is not diminished by another's — up to the point of genuine free-riding. I was no admirer of free-riders. I wrote at length about the colonial arrangements by which Britain bore the cost of defending trade from which the merchants of London drew the greater profit. The remedy I proposed was contribution proportional to benefit, not unilateral abandonment. Tearing down the institution because the cost-sharing is imperfect is like burning the courthouse because the docket is slow.

The deeper danger is what I would call the mercantile error applied to geopolitics: treating an alliance as a bilateral transaction in which each party extracts maximum advantage at minimum outlay, rather than as an institutional framework whose value lies precisely in its durability and predictability. A merchant who is known to honor his contracts commands better terms than one who renegotiates under pressure. A sovereign power that signals its commitments are conditional on short-term political convenience forfeits the credibility that makes those commitments valuable in the first place. The deterrent effect of an alliance is not the sum of its weapons; it is the certainty of its response.

I will mark the following as inference, not recollection, since I cannot see beyond the Politico headline: if the United States were to withdraw, or to make its participation so conditional as to be unreliable, the cost would fall not only on the exposed nations but on the very commercial order the United States has profited from since 1945 — the open sea-lanes, the predictable contract law, the stable currencies that allow the gains from international trade to be realized. These are not gifts from nature. They are public goods maintained by institutional commitment. Dismantle the institution and the goods evaporate.

The institutional question, then, is this: what framework disciplines the great powers into honoring their mutual obligations? I do not have a tidy answer. But I know the first step — and it is the step I always demanded of domestic markets too. Name the terms clearly. Enforce them consistently. Let every party know what is owed and what will happen if it is not paid. Ambiguity benefits only those who intend to defect. An alliance, like a contract, is only as strong as the shared expectation that it will be kept.