As California Bob says, when things don't make any sense, it's a good bet that somebody's lying. So here's my theory: somebody in Iran has been cut out of the oil money, so he's promoting this nuclear nonsense so he gets a big budget to spend on it, and when he buys stuff from the West he earns a bunch of brownie points and some big fat kickbacks. Not sure which would be more valuable.
As for this jet fighter, they are probably not building their own jet engines. As near as I can tell making a jet engine is a bit of a trick. Might even be a state secret. I don't think anyone really knows how they are made.