Perhaps Canadian politicians can be forgiven their slowness of uptake, given that Trump's comments are entirely unprecedented in modern U.S.-Canadian relations.

But there is one strong parallel for his remarks. While Trump's words may never move past the talking stage, they resemble the claims, pretexts and justifications used by Russia's Vladimir Putin before and during his invasion of Ukraine.

First is the claim that lots of Canadians want to become Americans. Some in Trump's Make America Great Again movement have explained the absence of a visible groundswell of support for annexation in Canada as a result of a harsh regime of censorship, as decried by Elon Musk and this week by Joe Rogan.

In a long op-ed he wrote in July 2021, Putin laid out his claim that the Ukrainian people, in their hearts, aspired to be part of Mother Russia, but their voices were censored.

"There are millions of such people," he wrote. "But they are not allowed to raise their heads. They have had their legal opportunity to defend their point of view taken away from them."