Blair, in a call with reporters at the end of a trip to Washington, said Canada was already an "essential partner" in the joint protection of North America, through NATO and the NORAD joint air defense program.

"Frankly, an integrated missile defense system for all of North America is the thing that makes sense to everybody," he said, rather than having it stop at the US-Canada border.

"And we've been able to demonstrate that we are a ready and willing partner, and that we have a great deal to contribute to the alliance."

Trump last week signed an executive order to start planning for an "Iron Dome" air defense system for the United States, like the one that Israel has used to intercept thousands of rockets.`

He ordered an implementation plan for the "next-generation missile defense shield" designed to guard against ballistic, hypersonic and advanced cruise missiles, including through the development of space-based interceptors, within two months.

The proposal has prompted criticism over its expected cost, and for the fact that the system is designed for short-range threats, making it ill-suited to defending against intercontinental missiles that are the main danger to the United States.

Blair's comments on extending US-Canada military cooperation come as the countries' ties face deep strains over Trump's threats to impose steep tariffs.