> I think this is unlikely, largely because there isn't a military need for them. Black projects have historically been for useful things. We're already at the point whereby the US or Russia alone could literally annihilate most humans on earth, with their existing, 1980s designs and materials.

That never been the case, even at the peak arsenal levels. USSR, and USA bombing each other into the iron age? Yes, but not much more.

The Norko h-bomb is a "black project." Israel's bomb is too. It's much harder to hide the fact of making plutonium, than what you are making with it.

USA, and Russia both have enough plutonium to do quite a bit with it, but most likely smelting it into smaller, higher yield weapons.

Tactical weapons were taken out from duty not because of them being "ineffective," or any humanism minded reasons, but because they were inefficient when it comes to plutonium use. Too much of it for "little" bang.

I heard of one 152mm nuclear munition having enough plutonium for making 2-3 proper h-bombs.

With START 2 being provisionally extended, but not followed by START 3, I see both Russia, and USA already preparing plans to upgrade their arsenals in 2026, the moment START 2 lapses.