[avar]

It's because before Bush invaded Iraq it would have been redundant to clarify that Bush said such and such in an official (written) capacity, as opposed to describing what the foreign policy goals of the US were at that moment. The two were synonymous.

Whereas when Trump was making overtures to annex Canada, it was useful to the rest of the world to explain that that's something the president was talking about that weekend, as opposed to signs that this might be something the US would actually do.