The bombers in Diego Garcia and American naval positioning is meant to intimidate Iran, and just in case Iran has any thoughts about responding to strikes vs. Yemen (which they won't), or Israel as it ramps up the Gaza extirpation campaign. They are also going to stay in striking range because the bigger picture is that the US, in a new objective, wants Iran to dismantle its entire nuclear program.
To be honest about it, I've always perceived their nuclear program as odd. Whether one accepts the argument that it's for peaceful energy or isotope research and medical use or not, one cannot escape the characteristic that it has provided Israel and the US (and previously, the Saudis) with a fistful of talleyrands to raise up and scream: "Look! They are building a nuclear weapon!"
Now, one might wonder why a country like Iran which has vast oil reserves which are fully developed and exploited, and will last for probable centuries might want to build a nuclear energy program? They had maintained it was so they would not use their own oil and could export it, and play up the medical applcations (which, to be frank, are fringey) - did their contention ever really make sense?
It is not hard to imagine why many have maintained that it doesn't make sense, and that Iran could do very well without a nuclear program at all.
Ergo, perhaps Iran's NP is to produce nuclear weapons, regardless of the Fatwah. So, we arrive at this point. What's new is that Iran's ability to militarily affect the entire region is on the wane, and in a big way.
There is a difference of opinion in the commentator world about whether Iran should quit its NP or not. I would strongly advise them to do so. The alternative would be horrific for them. Trump is going along with the Israeli determination to put an end to it (the NP), and although the Israelis and Trump would love to see the theocratic government of Iran overthrown completely, they would go along with a divestiture of the NP instead.
Ultimately, regime change is the long-term goal, but if Iran were more creative diplomatically, they could wiggle around it and perhaps convince the Israelis and the US to forego a color-revolution or black op contrived for coup d'etat.
Over the coming weeks, this is the dilemma Iran faces. It is different than before, because they are facing an elevated demand, not satisfied with inspections -- but demanding a full abandonment.
If they choose poorly, they will lose not only the NP but their own energy infrastructure, and face instabilities internally which they've never encountered before. I can certainly see Russia and China talking them into it. If they do this, they can avoid war.