Should Canada and USA reconsider building a missile defense shield over our shared threats with Russia, North Korea, and China?

No

We have that now. Under the direction of NORAD: North American Air Defense Command.

@kritiper Thanks.

I mean….‘missile defense shield’ is a pretty vague term. To some extent we have missile defense. AEGIS cruisers, adapted technology from Israel’s Iron Dome, and other techniques can shoot down SOME kinds of missile attacks and are mobile enough to be set up anywhere. I’d be surprised if places like Seoul and likely Japanese cities don’t already have some coverage, given how often the Kims have been lobbing missiles over their heads for “tests”.

But right now, we can only shoot down the slower moving and less primitive missiles with any kind of reliability. The ones that are the most dangerous we still can’t really. But we’re close and getting closer. We absolutely should be investing a TON of resources into this effort. It should be our ‘moon shot’. A reliable anti-ballistic missile system that can work against ICBMs moving at re-entry speeds, or maneuvering hypersonic cruise missiles would massively upgrade the planet’s safety against rogue regimes that usually don’t have large numbers of missiles.

When you’re dealing with strategic nuclear weapons, the game theory involved in mutually assured destruction gets weird if you introduce missile defense shields. Basically such a system only encourages massive stockpiling of nukes with the idea that some will overwhelm the defenses. Having more nukes makes the planet less safe. so paradoxically, the shields can make everyone less safe.