Iran Threatens U.S. With 'Harm and Pain'

Uranium isn't such an attractive fuel for a nuclear bomb anyway. True, it allows for the construction of simple gun-triggered devices, something plutonium doesn't allow (technically speaking, it's not so much the plutonium as other impurities which are a by-product of the process used for plutonium production, but let's not go into details) and is perhaps slightly easier to handle, but otherwise it offers little advantage over plutonium. Plutonium, on the other hand, happens to be one of the major by-product of the nuclear reactions that happen in nuclear reactors and is created from U-238 which is plentiful. Thus it's easier to generate large quantities of plutonium than highly enriched uranium. Even "better", reprocessing is a legitimate activity in the peaceful nuclear fuel cycle, allowing to extract plutonium from spent fuel and later use it again in reactors.

With that said, there are plenty of countries which could easily enough get the bomb if they so much as wanted to. Canada, Japan and Germany are the most obvious examples, simply because they happen to have a mature nuclear industry, producing their own reactors designs and equipment, the necessary knowledge, often a complete nuclear fuel cycle and a strong industrial base in general. On top of that, they're trusted by most countries, and missing plutonium would likely not be that much of an international concern. Who'd believe someone saying "The Canadians are getting the bomb!"?

Other countries with a lesser technological and industrial base could get the bomb as well, but with a bit more difficulty. It essentially comes down to whether or not they already have at least one nuclear reactor, and whether they already have, or could reasonably easily build a reprocessing plant. With that taken care of, sure, you still have the theoretical side of things to take care of, but first of all, you're not looking at a H-bomb, making things much simpler, and the knowledge needed isn't exactly "cutting-edge" these days. And your average desktop computer likely has more computing power than was available at Los Alamos back in the forties.

The reason Iran is using uranium, or, well, is suspected to be using it for bombs, is simply that they happen to have a uranium enrichment plant and reconfiguring it for highly-enriched uranium production is easier than building a reprocessing plant. Other nations would likely follow North Korea's path and go with reprocessing.

Jam it back in, in the dark.

I know that. Though as far as I know the ENIAC wasn't used for anything related to A-bomb development, anyway. However I do know they used various mechanical calculating machines made by IBM at Los Alamos. Not that those are exactly powerful either.

There's nowhere I can't reach.