Dude, only slowing them down is totally stupid.
No. Later is always better. Especially when it’s a totalitarian government that has problems with its people. Slowing them down give you the chance they don’t finish the project before getting overthrown.
And of course the biggest punchline is, and this is why we signed onto the stupid deal in the first place: there isn’t a damn thing we can do about it. We are not going to war with Iran to prevent them from getting nukes. Period. The people will not support it. Ever. The embargo was a joke. So in the end we had no options. There was no way we could make them stop. Write a fat check and hope for the best was all ever had.