Well, yes and no. If a nation like the US or Russia launched their entire arsenal, I doubt every one of them could be shot down. One of them would have to land somewhere.
People are also forgetting that remote detonation is a thing. Sneak a bomb into a city on a diesel truck or similar vehicle, have those agents leave the city, remotely detonate the bomb.
Or, like you said, create orbital nuclear weapons platforms. But attaching nuclear weapons to an orbital platform is very stupid. Tactically I mean, not morally (though it's stupid morally also). It is much more easier, simple, and cheap to simply use the
kinetic bombardment method. Programs to create these weapons have been in effect since the seventies (as far as official documents go, anyways. For all we know they could have been thinking this up since the 50's, or hell maybe even in the 40's as they were looking for ways to create super-weapons). NASA was working, in effect with a US arms corporation (either that or a US research department, I forgot) on a weapon like this in the 80's. But they're idea was much different than previous US Kinetic Bombardment or Soviet programs. You'd imagine at least a satellite-sized machine for this, right? While the US (NASA and whoever else) were working on one that would be the size of a gun. Very small, and very hard to hit/shoot and knock out of orbit. Also very cheap to make, and it's small size means that the US could effectively employ millions of them. Anyways it was the size of a pretty big gun (like Fallout's minigun, only three times that size), and the idea was to employ Gauss weaponry techniques, and mix them with kinetic bombardment techniques. This means, you'd have this small (but still big when compared to the size of a human) machine, that was basically a massive Gauss rifle. It would then shoot a tiny hunk of metal shaped like a bullet (but not actually a bullet. No gunpowder or anything, but a hunk of steel or possibly a cheaper, more lightweight and cost effective metal), propelling it at very, very fast speeds. It would then enter into orbit, and employ the techniques of kinetic bombardment, and from there, a tiny bullet just destroyed a small city (of about a million people), or a large part of a very large city (like Manhattan, Brooklyn, or Bronx of New York), and that's if it only shot one. The weapon was intended to have a rapid fire automation. If somehow, a weapon was made that could accurately target such a small thing moving as very fast rates (faster than any of our modern day military jet airplanes move, anyways), they would not cause a huge explosion in the sky (meaning no radioactive Fallout or geological problems who whatever nation is was shot down over), and the US would not lose millions and millions of dollars on a nuclear warhead. All they lost was a little hunk of metal. Whatever weapon that could be made to reflect this weapon, would also have to be able to do it several times in a matter of only a few seconds if the orbital weapon fired more than one. The US abandoned this plan and funded the money (which made up a large portion of NASA's research budget during the 80's. That's probably why NASA wasn't nearly as active during the 80's as they were during the 70's and 60's. I think the US funneled the money into developing our modern day stealth bomber, a newer version of the M Abrams tank, among other things...
Supposedly, this is just a rumor, but supposedly the US military is trying to restart Reagan's Star Wars program. But instead of the laser being used to destroy nuclear missiles, the laser would just be a weapon in itself. Really that's about as far as the rumor goes, so like I said it's probably bullshit but you never know.
