Arial Sharon, Nuclear Blackmail

This is a pretty terrifying news story that seems to have passed by the mainstream media (but not Juan Cole):

Alastair Campbell’s serialized memoirs contain a ... revelation that in conversations with President George W. Bush in late 2002, then Israeli Prime Minister Ariel Sharon threatened to nuke Baghdad if Saddam Hussein hit Israel with rockets again.

Those nuclear weapons that, of course, Israel will neither confirm nor deny that they possess! Is this really the behaviour of an ally?