Jeffrey Lewis often has smart things to say, but sometimes his articles make no sense, at least from a technical, on their face, perspective. If nukes really do fly, whether they fly over Russia or not is totally irrelevant. At a minimum, given only a heading, Russia would see that only the far east could be conceivably attacked, which is not a threat to the Russian nation, or its nuclear deterrent, and would not be the action of a power trying to attack Russia. In reality, satellites and radars would also be able to measure velocity, and this, even only with satellite and without radar, would make it clear that the target was NK. Russia might lodge a protest about its airspace being violated, but this would be comically minor compared to the rest of the diplomatic issues to be resolved after an actual nuclear attack.
Would the missile be in the atmosphere at the time it passes over Russia, or would it still be in space? I hit up Google and it wasn't helpful in answering this question.
If it is still in space, I'm not sure that Russia really has much ground to stand in, with regards to complaining.
This really has nothing to do with the altitude of the missile. Any ICBM that the US sends over Russia without talking with them first would be an extreme provocation, and would give Russia justification to do whatever they wanted (hopefully WWIII wouldn't result, but lots of other bad things could happen). This is not the same scale as North Korea test firing a missile over Japan (and look how nervous Japan got). Pre-coordinating a strike with Russia removes the time advantage that ICBMs have over bombers, and it would be a rare situation where Russia would give permission to let an American nuke overfly its territory.
Similarly, if Russia shot an ICBM over US territory at any altitude, the US would freak out and be justified in sanctioning the crap out of Russia. Unfortunately, the US is not in the way of any of Russia's targets (unless the target is the US), so it's mostly a one-way consideration.
I'm sure they'd be upset, but the USSR was the first country to overfly other nations with a man made object in space. I doubt they'd do anything other than yell about it? It's not like they could effectively sanction the US.
I am not an expert in these matters but, if I understand correctly, they can tell velocity and direction to see that it's not going to hit then. I'm not sure that it enters their airspace, however.
Are there any treaties or international laws regarding this? Again, Google is not being helpful.
It seems obvious that we shouldn't be too worried about things in space passing high, high above us - but the key difference is that ICBMs aren't designed to orbit. They are designed to fall out space, from a great height, and go bang. So while orbital whatever "just passing through" is relatively benign, a nuke doing the same thing is an active threat.
(Even more-so for American systems, which I believe can make course corrections at their apogee; so the current trajectory is not a guarantee)
Right, it made them nervous but, in the end, there was no major activity taken. I didn't know it there are any international regulations about it, or treaties around it. This is one subject Google is not very helpful with, though I may not know the correct terminology to search effectively with.
In the NK missile tests, Japan (rightfully) was pretty pissy but the end result has been largely nothing. My guess, and it is only a guess, is that it'd be much the same if, for some reason, we sent a missile through space and over Russian territory.
Though, I guess, Russia really wouldn't have much ability to sanction the US or enforce said sanctions. We don't really require anything from Russia and they are not close allies with anyone we do depend on.
Right, so you haven't heard any of the noise over NK sending up rockets then? Nukes are not spy sattelites, they are extremely destructive and symbolic weapons and you say the russians will be fine with an overflight based on their faith in the current administration... because that is really the argument to be had in this scenario: is instrument error more or less likely than a trumpian sneak attack?
A big part of the problem with flying over Russia (or any other nation) is that nuclear missiles are fallible mechanical systems. If it fails and drops out of the sky then you've fired a nuclear weapon at the wrong country. They might decide that's fine if it doesn't detonate, but that's by no means guaranteed. Would you be willing to take that risk?