What do you call this?

The same kind of false statement as claiming that they're about to be defeated, or that we're going to prevent them from ever getting a nuclear weapon.

These are claims that can't be fulfilled without, say, a massive ground invasion. That doesn't mean that Trump is going to send in a massive ground invasion. It just means he's wrong about saying that they're about to be defeated or going to be prevented from ever getting a nuclear weapon.

It's the same thing. He says they're going to be wiped out as a country, and that's the kind of statement that can't possibly be true unless we do a massive ground invasion or use nukes. But that doesn't mean we're going to have either a ground invasion or use nukes - it just means he's lying about them going to be wiped out as a country.

He's not coyly signaling that nukes are on the table when he makes these hyperbolic statements. He's just lying about what's going to happen in the future.