> Israel has to win but Iran only needs to survive
What is a win for Israel? They say their goal is to destroy Iranian nuclear capabilities (weapons and/or the means to produce those not actually clear)
How does we know that Iran has nukes?
Israel said so.
How will we know Iran's nuke capabilities are destroyed?
Israel will says so.
Unless there is some serious proofs, or some kind of event in the future, Israel can just say anytime they won, they destroyed everything.

Beyond this the US can intervene, bomb some sites and then claim everything is destroyed, and declare it as a win.