Israel would defeat Iran in a war, unless Iran plans on bringing allies in.
Not neccessarily. I would assume that the major coalition in a war with Iran would include the U.S., UK, Israel and maybe Saudi Arabia (though I think their role would be more on the logistical end as opposed to the combat end). If you consider technological strength, Iran is a bit behind them, but that is probably their only disadvantage. If you consider several other factors, Iran would definately have the upper hand.
Despite the fact that the Iranian military only has about 2.5 million members, Iran has a paramilitary force (the Basij) that has a least 13 million members that can be called out whenever neccessary. In the event of an inasion, there is little doubt that many more people would join the Basij forces, which would make the invasion and subsequent occupation of Iran a living nightmare for the U.S. and Israel. In addition, Iran is a relatively well-respected country on the world stage, so a U.S. and Israeli-led invasion of it would reduce the world opinion of both countries even further than it already is today. Also, Russia and China are very close allies of Iran, so they might intervene on Iran's side.
To make a long story short, war with Iran would make Vietnam and Iraq look like Grenada and ultimately result in a major defeat for the U.S. and Israel.
