Calling it a war is not quite accurate it would be an attack. But the very public bellowing from Israel would suggest it has more to do with delivering pressure rather than delivering bombs just yet.
Yes, I should say that Israel and the USA are on the verge of starting a war with Iran. There have been many acts of war leading up the bombing, including assassinations and cyber-warfare, but the rhetoric is especially heated now.
Every so often the Israeli leadership tries the argument that "if we don't strike right now, it will be too late and we'll all die in a mushroom cloud," but now they have Barak, Netanyahu and Lieberman all apparently on the same hawk page.
It's hard to tell if Israel is just bluffing, but it's a dangerous game in any case. It's also hard to tell if Israel gives a shit about getting a green light from Obama. After all, what could Obama do if Israel just went ahead and bombed Iran? We'd have no choice but to go along for the ride, wherever it takes us. For military purposes, Israel is as much a part of the USA as Wyoming.