This is going to make tensions extremely high. I hope it gets past that to the point where it calms down Israel, but for the moment it’s going to look to Iran like an extremely aggressive move, since they’ll see it as “You’ve taken away our threat of retaliation against attack and therefore made us vulnerable to attack.”
And even worse if Israel doesn’t calm down (seriously, Israel has a hawk problem) and starts using the shield as a way to threaten bombing nuclear facilities with impunity. Or if the US (also has a hawk problem) does the same.
No one – no one in this whole conflict – wants Iran to think it has to pursue asymmetric means, putting weapons or even (not bombs since they can’t do that technologically for many years and they’re too expensive, but) dirty bombs in the hands of unhinged and uncontrollable fringe groups? The thought is too horrible to contemplate.
Best possible outcome? The gulf allies and Israel feel safer because of the shield and the cooperation needed to bring it about. Iran somehow doesn’t do anything stupid. I really really hope so, but…