Shy Talk,
No-one in their right mind wants to start a war; equally the UN should not stand back and allow any more countries, especially those with religious fundamentalists in charge, to develop a nuclear device. Therefore sanctions and a united show of force are, IMO, the right way ahead.
Remember also that the Iranian religious mafia are quietly torturing and murdering thousands of Iranians who oppose them! So yes, just leave them to it, what can possibly go wrong? Uh, didn’t we do something like that in the 1930’s?