Some experts are worried about the cost and timeline of U.S. President Donald Trump's proposed Golden Dome missile defence system, which Canada has expressed interest in joining. They also say it could set off a space-based arms race that would escalate global tensions.

Trump's promises face skepticism from experts and would require big military trade-offs, including possible troop reductions in the Army.

More than once, Trump has said Michigan workers would play a role in the system’s manufacturing, although he did not mention the state during his Oval Office announcement this week. U.S. Sen. Jim Banks, of Indiana, at the Trump event said “Indiana is going to help you make it.”