Nuclear bombs require a precise order of events to actually detonate properly, shooting it out of the sky disrupts the chain of events required inside the bomb's mechanisms to achieve this. There's also no guarantee that upon a successful detonation as to what efficiency a nuclear bomb will fission, the Fat man bomb only had a %16 efficiency fission rate of the present nuclear materials.
This goes without mentioning that nuclear bombs require around-the-clock maintenance to stay in working condition, and we all know from the shredded tires on their trucks what the quality of maintenance is like in the Russian armed forces.
This is also assuming that it will ever escalate to launching nukes, which it won't, because the chain of command will likely refuse to get nuked in kind & nobody wants that. The only real reason Russia is able to invade Ukraine is because of an absence of a nuclear deterrent, because it frees up the region to infantry conflict. Launching nukes would mean Putin blows up the place he's invading after sending his own troops into the country, which is where the center of conflict is. The instant he does that, the world nukes Moscow.
No, WW3 will most likely end up just like the Cold War with people hesitating to launch the big bomb.
Also, you are not privy to the full extent of NORAD's capabilities, military secrets are secret, the only reason shitty ground missiles manage to get passed the Iron Dome is because of their close proximity, and there's the North Pacific ocean & Bering Sea sitting between Russia & North America.
No, your shitty, unmaintained nukes are not getting the West coast.
WMD WARNING!
