"Why?" is the hardest of the questions.

For any particular person, you can tell a story that satisfies "Why?". But for a large number of people, you have to answer "Why?" for one sub-group at a time.

In other words, there's not a single answer that will answer this in a satisfying way.

To answer a different question: It appears that the Israeli government and military wanted to bomb Iran again, and the United States executive branch and military decided to help out. This is an incomplete and unsatisfying answer. Sorry.