Donald Trump has been told "Canada is not for sale - ever" - as the country's PM Mark Carney visited the Oval Office for the first time.
But Trump insisted: "We'll see...time will tell".
The US President has frequently said he wants America to take over Canada - making it the 51st state.
And he frequently referred to Mr Carney's predecessor Justin Trudeau as "Governor Trudeau" - implying his country was, indeed, a state.
But he was given a calm, stern rebuke by Mr Carney during his first visit to the White House today.
Trump said he still believes Canada becoming the 51st state of the US would be a "wonderful marriage" - saying the two countries were "meant to be" one.
"I still believe that, but it takes two to tango, right?" he said.
READ MORE:
"It would be a massive tax cut for Canadians, you get free military, you'd get tremendous medical cares and other things. You'd get many advantages, but it would be a massive tax cut."
He added: "I do feel it's much better for Canada, but we're not going to be discussing that unless someone wants to discuss it."
Mr Carney pulled a face as Trump went on to say Canada effectively gets "free military anyway - because we're protecting you if you have a problem."
And he responded to the President's overtures, saying: "As you know from real estate there are some places that are never for sale. We're sitting in one right now. that you visited as well."
READ MORE:
He went on: "And having met with the owners of Canada over the course of the campaign, the last several months, it's not for sale. Won't be for sale, ever.
"But the opportunity is in the partnership, and what we can do together."
Asked by a reporter whether there was anything Mr Carney could say to him during the meeting that would get him to lift trade tariffs on Canada, Trump said: "No."
Asked why, he said: "That's just the way it is."
