There is an image that returns obsessively in Donald Trump’s political narrative: that of a generous, almost naive America footing the bill for Western security while its European allies, described as ungrateful freeloaders, sit at the table without putting their hands in their wallets.

It is a powerful narrative, easy to understand, perfect for the direct language aimed at the MAGA base. But it is, at best, a distortion of reality.

To understand why, one must start from a fundamental point that is systematically ignored in the public debate: NATO is not a common fund.
There is no grand treasury into which the United States pours resources that are then distributed to the other members.

The Alliance’s direct budget is relatively small, earmarked for the operation of shared structures and missions, and is financed by all member countries according to pre-established quotas. The US contributes significantly, of course, but it is by no means ‘supporting’ the others.

The real money supply, the one that is often evoked to demonstrate the alleged imbalance, is something else: it is national military expenditure. And therein lies the crux of the matter.

When Washington invests hundreds of billions of dollars in defence, it does not do it for NATO. It does it for itself.
To maintain global military superiority, to sustain its network of bases, to guarantee a capacity for intervention that no other country possesses.
Attributing this expenditure to NATO is a rhetorical device that serves to construct a narrative, not to describe reality.

Yet to stop here would be equally reductive. Because if it is false that the United States ‘pays for everyone’, something less intuitive but equally relevant is true: a substantial part of European military spending ends up in the United States anyway.

Over the past two years, more than two thirds of the military purchases of European countries – around $140 billion – have been made from American companies.
This is not a technical detail, but a structural element of the western defence system. When a European country decides to strengthen its army – buying fighters, missile systems, advanced technologies – it very often turns to US industry.
Not out of any form of automatic subservience, but because that industrial system has built up over time a technological, production and integration advantage that is difficult to overcome in the short term.

The result is a circuit that is rarely told for what it is: the US spends a lot on its own defence, but also benefits significantly from the spending of others. Not through direct transfers, but through markets, supplies, industrial interdependence.

This is where the Trumpian narrative really cracks. For while it is legitimate to demand greater commitment from the allies – and in many cases this commitment has indeed grown – it is equally necessary to recognise that the current NATO architecture is not a zero-sum game.
There is no clear winner and loser.
There is a system in which American leadership has a cost, but also produces economic, strategic and political returns.

And this leads to a question that is rarely asked clearly: what would really happen if the US decided to leave NATO?

The answer, beyond the obvious geopolitical implications, is less obvious than one would think. It would certainly be a huge blow to Europe, which would be forced to reorganise its defence system very quickly. But it would also be a significant blow to the American economy.

Because that flow of orders, purchases, and industrial integration that today binds the allies to the United States would inevitably be reduced in size.
Europe, deprived of the American umbrella, would be pushed to accelerate the construction of its own strategic autonomy, investing more in its defence industry. And every euro spent on autonomy would be one less euro crossing the Atlantic.

In other words, an eventual US exit from NATO would not only mark a political break. It would call into question an entire economic ecosystem that, over the years, has helped strengthen the American position in the world.

Then, perhaps, the real question is not who pays for whom. But how this system really works, and who benefits from it in the long run.

The answer does not lend itself to slogans. It is not useful for a rally.
But it is essential to understand why, beyond the bombastic declarations, NATO continues to exist. And why, despite everything, it continues to suit – even the United States.