We'll only know the "facts" when the midnight sun rises, at which point it's too late.

You can reasonably infer their likely future behavior from the past behavior and circumstances. Their neighbors have attacked them multiple times over the decades. Although their neighbor states are neutral or friendly in 2026, the issue is proxies which is to say Iran.

But the US president and a couple others would actually know in advance... extremely unlikely that IL would use nukes without at least a courtesy call, and a final opportunity to discuss. As I've said this may happened in the past, I'm confident that it did at least once although that might have a bluff on the part of IL to encourage our behavior in a certain direction.