There was the Darlington nuclear plant upgrades recently, which were completed ahead of schedule. Borealis was announced last year indicating new military research development. France had a nuclear sub in one of our ports, they already have nukes. I’m pretty sure they are going for them in secret and may already have one.
Not before 2050. The biggest hurdle isn’t the nuclear science, we can handle that fairly quickly. The problem is delivery systems. We agreed to a treaty that prevents us from building missiles big enough, fast enough, and long enough range to make nukes feasible. It was the trade off for being able to advance our nuclear research capabilities. Right now, I think there’s a lot of countries rethinking their stance on that treaty, but actually developing those platforms is going to take time, even if that treaty goes away.
The warhead is the easy part.