"I'm not in a position to evaluate the numbers. We're going to bring a budget out in the fall, and when we bring a budget out we'll have a lot more to say about what we're going to do," McGuinty said on his way into the weekly Liberal caucus meeting.

On Tuesday, in a social media post, Trump said it would cost Canada $61 billion to join as a sovereign country but nothing at all if it became a U.S. state.

Trump claimed that Canada is "considering the offer."

When asked about Trump's comments, Prime Minister Mark Carney said he won't negotiate in public.

Canada's Ambassador to the UN Bob Rae said that "in another context this would be called a 'protection racket'," in a social media post.

Several Liberal MPs said that the renewed 51st state talk is not on the table as they entered their weekly caucus meeting on Parliament Hill.

Trump announced plans for a complex missile defence system modelled after Israel's "Iron Dome" earlier this month and claimed it would cost US$175 billion.

The Congressional Budget Office says that the space-based components alone could cost more than half a trillion dollars over the next 20 years.

Lt.-Gen. Eric Kenny with the Royal Canadian Air Force said that Canada is in "exploratory discussions" with the U.S. about what "Golden Dome" membership may look like.

"I have not been told that (dollar) figure. I did see the tweet. At this stage, I say it would be early exploratory discussions about what our participation may be, but it doesn't take away from our focus," Kenny said at the CANSEC conference in Ottawa.

He added that Canada's focus is to ensure there is an integrated missile defence system that's "suitable" for Canada and takes national sovereignty into consideration.

In 2022, Canada announced a $38.6 billion plan to contribute to Norad modernization over the next 20 years.

— With files from Kelly Malone in Washington and Kyle Duggan in Ottawa.

This report by The Canadian Press was first published May 28, 2025.