Not to be too particular, but let's get a few things straight.
First, Carter did in fact order Delta into Iran to free the hostages, but they screwed it up. It's funny how conservatives give Obama no credit for taking out bin Laden -- it being the SEALs who did all the work -- but they simultaneously give Carter all the blame for the Delta's failure.
Second, North Korea actually went nuclear on Bush's watch -- not Clinton's. It was going to happen eventually but Bush gave them the excuse when he labeled them part of the "Axis of Evil" -- in violation of an accord we had with them.
Third, while I refrain from engaging in conspiracy theories, there are more than a few respectable individuals, including one from Reagan's team, who allege that the release of the hostages 20 minutes into Reagan's term was anything but kosher.
Finally, Iran is going to get the nuclear bomb. You can't stuff that genie back in the bottle. They will not use it against Israel as they are not suicidal. Mutually assured destruction will continue to operate as it has for the last 60 years. We might as well get used to the idea that we will have to deal with Iran on the diplomatic front, and Israel had better figure that out as well. The last thing we need, or can afford, is yet another unwinnable ME quagmire.
Ok, lets see, I never blamed Carter for the Failure of the Special Forces raid. I said he did almost nothing, I did not say he did absolulely nothing. Since I actually know a fair bit about that operation. The military planners wanted to include all service branchs in the operation, While the USAF had refuelable helecopters, the decision was made to use non-air-refuelable helocopters from another branch. The USAF only had a few refuelable C-130 Aircraft which would be necessary (the C-130 being the only cargo aircraft with enough size but still able to land on open desert) so two Aircraft belonging to the 7th ACCS, Biloxi AFB Mississippi where chosen for the operation. The failure point of the operation was when the helocopters had to land to be refueled from bladders onboard the C-130s. During the refueling, a fire was ignited, all the helecopters either burned or had to be abandoned, USAF EC-130E tail number 62-1809 also burned. The remaining personnel were loaded about aircraft EC-130E tail number 62-1857. The C-130 was over takeoff weight and nosed through a sanddune bending the airframe on the way out, but it came home. (BTW, thereafter, during engine starts, you could see 1857's tail section would kind of go around in a circle instead of the normal side-side vibration and the Pilots swore it flew a bit crooked). So, no, that incident cannot be blamed on Carter other than he appointed the Generals who made the decision.
However, had Carter not decimated the military, then it would of been a more credible threat and either the hostages could of been returned sooner or would never have been taken in the first place. The decision to release the hostages at that specific time had nothing to do with some secret conspiracy. First, because Carter had publically praised the Shah of Iran as being America's greatest ally, the leaders of the revolution (Ayatollah Komeini and others) would not release them as long as Carter was President. Second, all they really knew about Reagan was the he was some kind of cowboy who would take a "a shoot first, ask questions later" type attitude. In other words, instead of a secret Special Operation, Reagan would unleashed full military power, something that Carter would never have done on anyone except maybe the Soviet Union if they had started it and even that exception is questionable.
I know for a fact that it was under Clinton when NK completed it's work on "the bomb". No other information will be provided by me about details because of the sources of my information. Feel free to disagree all you want.
No, Iran will not get nuclear weapons, either Israel, the US or the US and Israel (no offence to our fine British brothers, but, I don't know if some of you want in on this one or not) will distroy them before they can complete the work. If they have not already finished it or will finish it very soon, then either Israel will lose and be destroyed or Iran will lose and be destroyed. If you haven't been paying attention, Israel, unlike Obama, doesn't give a damn what the UN, Europe or anyone else thinks about it. Just like their raids into Syria, the Raid on Entebbe, sending the Moosad to kill the teriorist from the Olympic killings and many other operations they have carried out, they will do what they feel is necessary and everyone else can go to hell if they don't like it. Lets face it, Israel does not have a very good track record of letting a bunch of Prattling Socialist at the UN dictate their actions. And unlike South Korea when dealing with NK, Israel isn't going let whether the US will support them or not alter their actions.