The Russians will sit by while Israel "takes out" Iran but will "step in" and go head to head with the U.S.?
If so, the Russians will do what to the U.S.? Pit a Russian conventional expeditionary force against the U.S. forces already in theater? Go the Mutually Assured Destruction route against the U.S. for the sake of Iran?
From a purely logistical perspective, how will the IDF carry out the sustained conventional air campaign necessary to "take out" Iran's hardened sites?
The U.S. has the miliatary assets necessary for such a task right across the borders from Iran. Israel does not.
Short of a first use nuclear strike against Iran, the task of "taking out" Iran is beyond Israel's military capabilities. The Israel of today is incapable of "taking out" Hezbollah in southern Lebanon.
The only way that "Israel" will "take out" Iran is if the U.S. paints these
on our aircraft in theater, and, after the month-long air campaign to "take out" Iran, the U.S. says, "The Israelis did it. That's our story and we're stickin' to it!"