The arithmetic is as simple as it is dizzying. In the first five days of the conflict with Iran, the United States and its Gulf allies fired around 800 Patriot missiles. American production, across all manufacturers, amounts to less than 750 per year. There is no need to be a mathematician to understand: since March, Washington has been facing a stock issue. This is all the more pressing given that building a Patriot missile, the best-seller of the US arms industry, takes more than two years.