"Israel gave thought this spring to launching a strike on Iran but was told by Bush that he would support it and did not expect to change that view.."

In the Guardian, here

"..Bush's decision to refuse to offer any support for a strike on Iran appeared to be based on two factors, the sources said. One was US concern over Iran's likely retaliation, which would probably include a wave of attacks on US military and other personnel in Iraq and Afghanistan, as well as on shipping in the Persian Gulf.

The other was US anxiety that Israel would not succeed in disabling Iran's nuclear facilities in a single assault even with the use of dozens of aircraft. It could not mount a series of attacks over several days without risking full-scale war. So the benefits would not outweigh the costs..."