A Ford-class carrier costs about $13 billion and takes years to build. The threats being aimed at it are cheap: drones, cyber intrusion, space-based targeting. That imbalance is what makes the carrier such a magnet, because damaging a multibillion-dollar warship draws attention in a way that sinking a frigate does not. Losing one would be catastrophic in military, financial and political terms at once, and that raises the stakes every time one s…