Could countries be producing nuclear weapons without anyone knowing?

With the US’s FU to our allies, I wondered if any of them have decided they need the N-card that gives them at least some immunity from the rash decisions of other leaders. I’m sure many countries have the knowledge and resources to build them, but could they without anyone’s knowledge? Obviously a test would be detected, but testing may not even be necessary at this point. I guess the question would be why? If it’s meant to be a deterrent, it doesn’t do much good if no one knows you have them.

It would be quite difficult because most U.S. allies are democratic nations with considerable transparency. To get a nuclear-weapons program going would be extremely hard to hide from such media. As for movement of uranium or plutonium or enriching of it for a Teller-Ulam device, that would probably be hard too.

The biggest issue is that any US ally that has a strong need for nukes would be under scrutiny because its need for nukes would be well known.

The development might be secret, but the test would still be necessary. Not to find out if it works, but to clearly and unambiguously demonstrate to the world that you have them. Because there’s no benefit to having nukes unless everyone knows you have them.

Israel is thought to have them, although its official policy is to neither admit or deny. South Africa briefly developed a bomb but later dismantled the program.

Which is proof that they don’t. An official policy of keep 'em guessing makes plenty of sense for a nation that doesn’t have them, and no sense at all for a nation that does.

From a purely deterrence theory / military perspective I’d agree w your thoughts.

But from a total international political perspective and given Israel’s positioning in the wider world, there is a benefit to not being unambiguously labeled a nuclear proliferating pariah state on par with North Korea and Iran.

It’s also the case that Israel long ago achieved their state of semi-implausible plausible deniability. The world was a different place in 1966 a mere 60 years ago when they (probably) got their first deployable weapon. If e.g. Saudi Arabia has since satisfied themselves that Israel isn’t bluffing, well then specific deterrence works as to e.g. Saudi Arabia.

Except that, as demonstrated three years ago, Iran has since satisfied themselves that Israel is bluffing.

So intelligence agencies, journalists and whistleblowers all over the world are wrong? What is your evidence of this?

Back to the OP, enriching uranium is difficult. The centrifuges needed to do that are easier to detect. However newer technology involves enriching uranium using lasers instead. These are easier to hide and harder to detect. I don’t know if any nations are using this technology right now, but sadly it could make it much easier to enrich uranium in secret.

An old adage is that no one who has tried to make an atomic bomb has ever failed to do so. Not sure if that is still true. Your second point was a big part of Dr Strangelove.

I’m sorry, that’s a little too telegraphic for me.

What exactly did Iran do or not do and what exactly did Israel do or not do that has convinced you (and perhaps Iran) that Israel is bluffing?

It seems me that there is a horribly thin line here. Nobody wants to be the first to actually use a nuke since WWII, because they would automatically be the Worst Villain of the age.

But given Israel’s technical capabilities, I’d be very surprised if they didn’t have nuclear weapons?

The other aspect is that while the Nagasaki implosion-plutonium device is hard to make, the Hiroshima gun-type assembly is highly simple. It’s basically just two pieces of uranium-235 rammed into each other in a metal tube. (with some more complexity, but that’s the gist of it.) That might be much easier for a nation or organization to do in secret.

Israel might already have tested a nuclear weapon; at least a former US President appeared to believe it did: Vela incident - Wikipedia

Israel does bluff on a lot of stuff, and they have not tested anything recently, but they have nuclear materials (enriched plutonium), installations, scientists/engineers, and delivery systems. So does Japan.

Are these capacities of Israel and Japan greater or less than those of Iran?

I have to confess I lack the expertise to give a definitive answer to this question. On one hand, those two countries are not currently under sanctions. On the other hand, Iran does have a bunch of plutonium and ballistic missiles as well, so, sure, they could use it. I am not in a position to say to what extent what could be done “without anyone knowing”.

Its not just that Israel has nuclear weapons, they developed them 60 years ago. Supposedly around 1966-1967.

I’m not following you here.

Iran has hit Israel (and vice versa), but I am not sure what the red lines are on either side to provoke a nuclear response. (NB the problem with that is the usual: the only winning move is not to play). Also one has to take into account alliances (e.g. if Israel had (hypothetically) tried using nukes in 1973, well, Soviet nukes were already deployed in Egypt).

Short answer is a few conventional BMs not targeted at strategic targets are apparently not enough to ensure who is or is not bluffing