if Russia and China don't want one. They are capable of squeezing the gonads of the west without loss of one life, and don't think they won't if they think an attack on Iran is dangerous to their interests.
China has the ability to send the U.S. economy ( and the rest of the west with it)into a tailspin by dumping U.S. bonds. Russia can find the need to do maintenance to its gas lines to western Europe in Dec. Jan. and Feb.
You don't think they'll play hardball? And there's no nuclear blackmail against them.

Hey, Grandma Moses started late!