The New Yorker: Watching Lebanon Aug 14 2006 by Seymour M. Hersh
Sy Hersh (widely speculated to have lots of good CIA informants) writes in the New Yorker that the Bush administration needed the Israelis to invade Lebanon so that Hezbollah's long-range missiles could be removed (so that when the USA attacks Iran there won't be any possibility for retaliatory strikes
Israeli intelligence estimated at the outset of the air war that Hezbollah had roughly five hundred medium-range Fajr-3 and Fajr-5 rockets and a few dozen long-range Zelzal rockets; the Zelzals, with a range of about two hundred kilometres, could reach Tel Aviv. (One rocket hit Haifa the day after the kidnappings.) It also has more than twelve thousand shorter-range rockets. Since the conflict began, more than three thousand of these have been fired at Israel.
[...]
“The Israelis told us it would be a cheap war with many benefits,” a U.S. government consultant with close ties to Israel said. “Why oppose it? We’ll be able to hunt down and bomb missiles, tunnels, and bunkers from the air. It would be a demo for Iran.”
The article contains a lot more detail and speculation about possible splits within the Whitehouse Bush/Cheney vs Rumsfeld vs Rice and the misdirection of information to directly bypass the NSA and end up in directly in the new intelligence structures created by Cheney.