That's the image people get of nukes based on the most powerful ones of all, the metropolis-vaporizing "strategic" ones. But that's not what all nukes are like, and it's not the kind of nuke that was specified in this case. In this case, they said "tactical" nuke. That's a rather small, weak nuke, on the order of a few dozen kilotons instead of hundreds of kiltons or multiple megatons like most people think of. They'll blow up an enemy encampment a few miles downrange of your own troops without risking your own troops, or blow up a small section of a city (like a particular neighborhood or a shipping/warehouse/factory district) instead of the whole thing.