Will world back Israel if it pre-emptively strikes Iran?

In 1981, when Israel destroyed Iraq’s nuclear reactor in a pinpoint airstrike, the whole world – including the United States – condemned it. Years later, when it became known that Iraqi leader Saddam Hussein had been working to redevelop nuclear weapons, much of the world belatedly commended Israel for its prescience.

I fail to understand why we're waiting. Allowing Iran to have nuclear weapons is insanity.