Unlike Ronald Reagan's 1980s Strategic defence initiative, a.k.a. Star Wars, the anti-missile defence shield, into which Canada currently seems to be placing some serious stock, is quite realistic and technologically sound. In fact, over two decades ago the tech had impressively (at least to me) proved itself to be on solid ground, though I feel that it could’ve already been by now solidly established as a fully functional defense shield.
One need only note the success of the Patriot batteries stationed around Israel during Desert Storm.
If I recall correctly, the Patriot missiles had been barely developed with no practical testing, thus they had to be field tested during actual warfare. Only one scud made it through the defence shield intact and another after being severely damaged, though both did not result in death, injury nor even notable damage. Had the system been shy of competent, let alone a failure, there’s no reason to believe that the nuclear-armed nation of Israel was bluffing when it promised to retaliate against Iraq if the Patriots failed to deliver and Israeli casualties were incurred.
Unfortunately, whatever small degree to which the U.S. has thus far developed its shield technology in actual hardware would only serve to intercept ballistic missiles targeting nations that are U.S. friendly or their protection is in U.S. interests.
That kind of act could motivate some nations—most worrisome being rogue nations such as the bizarre-behaviour North Korea via their Great Leader—to find other means to compensate for their new great disadvantage. For example, they could expand their nuclear arsenal while collaborating with their own friendly nations (however few) to achieve the means to overwhelm the biased anti-missile shield.
A good means of avoiding such dreary anti-productive measures-thus-counter-measures would be to ensure all interested ‘sides’ that the anti-missile defence shield would be independently programmed to intercept all airborne projectiles regardless of their origin. The system would monitor the planet’s air space and launch anti-missile defensive measures, equipped with latest computer-systems-hacking fail-safe technology.
The naysayers of such a universal defence shield should suggest other plausible ways through which to avoid nuclear-exchange devastation anywhere, let alone everywhere. As for those who say such a shield would be too expensive—just how much is Earth and humanity worth?