Hillary Clinton's comment about nuking Iran in retaliation if Iran attacked Israel with nuclear weapons has drawn derision from at least one well known liberal who I greatly admired.
Allow me to present a different prospective.
In the late 1940s, nuclear arsenals held by the USA and the USSR (nee Soviet Union) began their growth towards the enormous death dealing capacity that exists today. The COLD WAR was born. Air force planes flying shotgun in the sky ready to attack, nuclear submarines trying silently as possible to get positions in the ocean to fire nuclear missiles, silos that had more nuclear missiles that could be launch from the USA -- all became the insurance that told the USSR that anything it did to destroy us or our allies would guarantee their own destruction also. It borders on dark humor to call this standstill by the acronym MAD -- Mutual Assured Destruction. AND IT WORKED. War ceased for those countries under each superpower's protective umbrella. With great armies of both sides staring at each other in Europe, no engagements took place that rekindled more war. Vietnam was unlucky, it had no protector. Neither Tibet. Formosa, now Taiwan, was and still exists as an independent entity because there is tacit agreement on how the USA will talk about its future vis-a-vis China, a late bloomer as a nuclear arsenal possessor. South Korea and Japan live free.
Senator Clinton's remark made it clear to Iran's mullahs -- who really control that country -- that destroying Israel by the use of nuclear weapons was unacceptable. Iran should best think of Israel as America's 51rst state, since, if she were president, Iran would not exist after such an attack. Sobering--you might think she was mad, but actually she was invoking MAD!
ADDENDUM: THE FIRST 3 POST TO THIS ARTICLE POINTED OUT A MISTAKE I MADE. THE HYPOTHETICAL QUESTION PUT TO SENATOR CLINTON WAS ONLY ABOUT A NUCLEAR ATTACK BY IRAN, NOTHING SAID BY ITS PRESIDENT.