> ...there is no way the US is going to shoot down Israeli
> planes (and I don't think the Iraqis have the capacity to do so). That's
> not participation; that's your bluff being called.
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This presupposes that the Israeli political and military leadership believe
they have a serious chance of doing anything more than briefly retarding
Iran's acquisition of nuclear weapons. They are probably under no illusions
about that; Iran is a more formidable enemy, is much better prepared, and
can't be hit with the same impunity as were Iraq's primitive nuclear reactor
at Osirak in 1981 and, more recently, Syria's alleged facility near Appolo.
I expect US and Israeli strategic thinking is now focused on how to live with a nuclear-armed Iran within the framework of a Middle East doctrine of Mutual Assured Destruction. The template is the nuclear stalemate between the US and the USSR, which was also preceded by much public threatening of a US first strike against the Soviets in the early 50's. It presently defines the standoff between India and Pakistan and between the US and it's Asian allies and North Korea.
The most exhaustive public examination of the prospects of a strike against Iranian nuclear facilities is by the well-known military analyst Anthony Cordesman and his colleague Abdullah Toukan at the Center for Strategic and International Studies (CSIS) in Washington. They concluded that it was very unlikely to succeed in even delaying the development of an Iranian bomb. The study can be downloaded from the CSIS site, but it was also widely publicized in Israel, including in this detailed report by Ha'aretz several weeks ago which makes very interesting reading:
http://www.haaretz.com/hasen/spages/1085619.html
Cordesman and Toukan would necessarily have had contact with US and Israeli military planners in the preparation of their study.
Also worth noting in this context is that the Israeli general staff, or at least some part of it, now accepts that the US invasion of Iraq, which it strongly encouraged, was a major blunder because it strengthened Iranian influence in the region. See:
http://feeds.washingtonpost.com/~r/wp-dyn/rss/world/index_xml/~3/289229352/AR2008051202957.html
You also have to think that similar retroactive assessments by the Israelis of their operations against Hezbollah in Lebanon and Hamas in Gaza have also curbed their appetite for a much riskier and dangerous adventure against Iran.
All of this, independent of whatever pressure for restraint the Americans, acting in their own wider strategic interests, exert on the Israelis.
So, while always possible, I think an Israeli strike is quite unlikely.