Also: "Reality is that which, when you stop believing in it, doesn't go away." - Philip K. Dick

How desperate, and appropriate.

That's what the nuclear-capable nations' militaries hoped for, but it didn't turn out that way. As already stated in a number of posts above (and argued in TFA), the distinction between tactical and strategic nukes is very difficult to make. Nuclear weapons are simply too powerful (and too dirty, regardless of the size) to be useful in a tactical setting.

One party which seems to have recently realized this is, wonder of wonders, North Korea. There are strong indications that their designed yield was about 4 kT. A piddly tac nuke, right? Well, as mentioned in the discussion after the referenced article, imagine those 4 kT going off in the heart of Seoul or Tokyo...

They didn't sign anything -- see this article. Missile launch ban is the consequence of the UNSC Resolution 1874, adopted after the North's second nuclear test. I don't think that the North is irrational -- just quite determined to preserve the regime and prepared to play provocative moves to that end.

Thank you for reminding me. I'll be twitching for the rest of the day. Funny how much outright crap one can remember -- I thought those neurons have long died off out of sheer disgust.

For the mercifully uninitiated, SCO Unix had a baroque system of little configuration files, object modules, a severely handicapped C compiler, and a similarly crippled linker for the purpose of modifyng kernel parameters and installing third-party drivers, both of which required re-linking the whole kernel (sysctl? dynamic data structures? run-time linkable modules? never heard. OK, it was the early '90s, but still.)

SCO, in their infinite wisdom, tried to make driver installation "user friendly": you would unpack the archive, start the installation script, and a few minutes later reboot to a freshly built kernel. Of course this failed to account for buggy scripts, weird configurations, and cargo-cult admins, any of which could make an unholy mess of the system and/or render it unbootable. I've had the dubious pleasure of cleaning up a number of such messes.

Criticality -- the point at which a fuel assembly can sustain a nuclear chain reaction by itself.

Critical mass -- the smallest mass of fuel for which the criticality is reached; depends on geometry, density, temperature etc.

So the GP's usage is correct. To be really precise, one could note that weapon fuel should go from subcritical to prompt critical to achieve explosion, but that would be nitpicking in this context.

O'RLYEH?

Scale-wise, the Sun could probably swallow the whole Earth and get only mild indigestion. However, launching anything into the Sun is a waste of energy; it's cheaper to punt it into interstellar space, as discussed here.