The Canadian government said it is in talks with the US over joining its proposed "Golden Dome" missile defence system, aimed at countering "next-generation" aerial threats.
Prime Minister Mark Carney's office said there are "active discussions" between Canada and the US on security, including on existing and new programmes like the Golden Dome.
US president Donald Trump unveiled the plan for the new missile defence system earlier on Tuesday, announcing an initial sum of $25bn (£18.7bn) to build it. He added Canada has expressed interest in joining.
There are doubts from experts on how the US would deliver a comprehensive system and it is unclear how Canada would participate or how much it would pay.