Why has Iran been enriching U235 to 60% for years now, when nuclear power reactors only require 3-5%?
There are some medical uses for 20%. One might argue 60% is easier to transport and then dilute to 20%, but I wouldn't.
I think Iran could have built a nuclear DEVICE 20 years ago if they wanted. Then they realized they have a problem with delivery. Our first A bombs weighed 10,000 pounds. A country today building it's first DEVICE wouldn't care about weight, initially, but to build a BOMB, they would. So, that means at least second generation.
Then to deliver it, you really need a missile with throw weight and range, and you need to turn said device into warhead, which means fusing and reentry shielding and decent targetting ability (CEP). So, I THINK Iran stopped weapons development, except in theory, and focused on missiles. They now have a missile with a 750 kg throw weight and range to hit Israel. That could be enough.
So, they now need an operable warhead that functions in reentry and appropriate fusing etc. that weighs 750 kg or less. That would be difficult. So, I SUSPECT they wanted to have 60% to make it a short term operation should they decide to make said warhead.
Here's the rub in all of this, our SECOND A bomb used plutonium, not enriched uranium. Most nuclear weapons today use Pu, not U (or in addition to U). Pu is more efficient. Pu can only be made in special nuclear reactors, then it has to be refined and purified to the preferred isotope of Pu. Were I to want an A bomb, I'd focus on Pu, not enriched U.
