David Lammy thought he was reassuring Canadians. During his visit to Canada – for a meeting of G7 foreign ministers– he was asked about Donald Trump’s claims that the country should become the 51st state of the US. The UK foreign secretary stressed that Canada is a “proud [and] sovereign nation”, and – in his view – would remain so. When pressed further, he invoked Canada’s shared history and monarch with the UK, and our work together during the second world war.

Canadians are already well aware of that shared history, and how Britain has long benefited from its Commonwealth. My 96-year-old father just missed the age of enlistment in support of Britain in the 1940s but his two brothers, young boys from the Canadian prairies, lost their lives as RAF bombers. One of them is buried in the beautiful Commonwealth war cemetery in Harrogate.

King Charles retains a role. Constitutionally, he remains head of state. So was it too much to ask that Mr Lammy might add a few words – something like “we support Canada in its efforts to remain a strong, sovereign country”? Or, leaning in a bit further, a hint that the UK is “concerned” (a nice diplomatic word) about efforts to undermine our territorial integrity?

It’s commonly said that politics is too often about words and not deeds. And yet words matter too, especially in the era of President Trump. Over recent years, we have seen his utterances initially dismissed as crazy – nothing to worry about, mere provocations or opening gambits in a negotiation. But over time, with every reiteration of the provocation – Barack Obama may not be American, Trump really won the 2020 election, the EU was set up to “screw” the US – those currying favour with Trump repeat the charge, diffuse it to various audiences (a process described as “sanewashing”), and ultimately enable him to act on the underlying logic of his words.

So it is with Trump’s suggestion that Canada “only works” as a US state, and that Canada and the US are divided by an artificial line. How beautiful the geography would be if that border disappeared!

Here in Canada, Trump’s first mention of annexing our country was thought to be a joke. Once upon a time, Canada’s G7 allies might have been forgiven for the same reaction. But no longer. If Trump is to be taken seriously but not literally, then the underpinnings of his predatory approach to international affairs need be acknowledged and factored into the foreign policy of all nation states.

There are many scenarios actively under discussion in Canada – some more extreme than others. The US may not be about to invade us with military force, but it could undertake various actions to challenge our sovereignty, unity and territorial integrity. That could start with the hollowing out of our economy to move production and wealth to the US, but extend to revising existing agreements on North American water resources (something Trump raised in discussions with the outgoing prime minister, Justin Trudeau), coercive deals for access to key resources, and subverting longstanding mechanisms for security and defence cooperation. There could also be challenges to Canada’s control over its Arctic region and interventions in our democratic processes. In a recent survey on foreign interference, Canadian respondents put the US second on the list of countries most likely to interfere in our upcoming election, ahead of Russia and India.

At last week’s G7 meeting, Trump’s secretary of state, Marco Rubio, took “sanewashing” to new heights by presenting a two-sided debate about Canada’s sovereign status: “There’s a disagreement between the president’s position and the position of the Canadian government.” We can agree to disagree on this matter, he suggested, but work together on a “bunch of other things”.

Let’s be clear on the heart of this difference of opinion. The governments of Canada and the US are disagreeing not only on the wording of a G7 communique on Ukraine (though they did so behind closed doors), or whether the G7 should act against “shadow fleets” circumventing sanctions against Russia (an initiative that Canada pushed but failed to see emerge as a firm G7 commitment). The disagreement is about whether Canada works as a sovereign country. While Rubio insisted this wasn’t the focus of the G7 meeting, the audacity of the Trump administration’s predatory posture on territorial integrity, whether with respect to Greenland, Panama or Canada, demands a clear response.

Lammy echoed Rubio’s line that there are areas where G7 allies disagree but argued that the UK’s goal is to find unity in a troubled world. This presumably explains why he expressed “regret” and “disappointment” about the trade war, but wouldn’t condemn US tariffs, and why – unlike Germany’s foreign minister and the EU high representative for foreign affairs and security policy – he would not be drawn on the US administration’s threats to Canadian sovereignty.

Having studied and taught international relations at one of Britain’s finest universities, I’m not naive about the UK’s national interests or the imperative to nurture its “special relationship” with the US (by the way, Canada has long thought it had one of those too). But again, words matter. They need to be spoken in public, not just behind diplomatic closed doors, with an eye to multiple audiences.

Surrendering to the “sanewashing” about Canada’s sovereignty is not in the UK’s interest, either in the current context of tariff wars, longer-term challenges to transatlantic economic and security cooperation, or broader global stability.

Canada’s new prime minister, Mark Carney, who visited the UK on Monday, has underscored that Canadians aren’t necessarily looking for our allies to “say nice things” about us. As “masters in our own house”, he said on the day he was sworn in, we must take our own steps to ensure our survival. Canadians are becoming acutely aware that, given our particular geography and history of interdependence with the US, we stand alone in this new predatory world. But as with the members of our second world war generation, we have long memories: we will remember who stood with us at a time of great consequence for our country, with both their words and their deeds.