This makes me think Trump is backing down and accepting Iran's latest terms for an MOU.
Based on his past behavior, when Trump is about to escalate, he tends to stay quiet or make vaguely deescalatory comments.
On the other hand, when he's about to give in, he'll put out some grandiose, attention-grabbing threat, so he can then pretend like it was the other side who rolled over out of fear.
I think, and hope, that that is what he's doing here.