US President Donald Trump was deterred from launching a broader attack on Iran by concerns over the cost of defending against the retaliation that would follow.
At the heart of the problem is a stark cost imbalance. Iran can launch a relatively inexpensive drone costing tens of thousands of dollars or fire a missile, while the United States may have to counter it with a Patriot or THAAD interceptor or a naval missile priced in the millions. Even a technically successful defense can therefore prove economically disadvantageous.
More important than the book value of the missiles is their opportunity cost – the value of what must be sacrificed when they are used. An interceptor fired in the Middle East today is no longer available in a potential conflict over Taiwan or to support European allies.
The strategic value of those remaining therefore rises sharply as stockpiles shrink. From an economic perspective, each additional interceptor becomes more valuable than the one used before it.











