A bright flash will signal the attack on Israel intended to destroy the "little Satan."

At that moment all the debates about President Obama's legacy and motives, all the charges and counter-charges about details of inspection regimes and anti-sabotage agreements, all the counting of centrifuges and tallying of Democratic senators who dare to go against their base will be forgotten.

None of it will truly matter on that day, any more than Chamberlain matters to discussions of the start of World War II today. Neville Chamberlain is remembered as the high priest of appeasement, but so what? The war came, tens of millions died, and the peace followed and the rebuilding. Poor Neville — but he didn't get marched off to the death camps, did he?

President Obama's catastrophic tenure at 1600 Pennsylvania, like Hillary Clinton's catastrophic tenure at Foggy Bottom (the Russian "reset," the trial run for the Muslim Brotherhood in Egypt, the launching of the Libyan chaos, the hasty withdrawal from Iraq and the subsequent vacuum into which the Islamic State moved) will be remembered hardly at all once Iran gets the bomb as now guaranteed. Guaranteed. That is the bottom line of the Iran "deal." Iran is now a legitimized "soon-to-be" nuclear state. Children born today won't have started "world history" in 9th grade before Iran has nukes.

Why is this nuclear nightmare different from all other nightmares? For the same reason that the terrorist who killed four Marines and a sailor is different from every other murderer in the United States this weekend: The Tennessee terrorist wanted to die and take as many of his "enemies" with him as possible. He appears to have been a Sunni Islamist fanatic. Iran is full of and run by Shiite Islamist fanatics.

Iran sponsors and protects Hezbollah. On July 18, 2012, a Hezbollah-sponsored suicide bomber attacked a bus at the airport in Burgas, Bulgaria. The bus was carrying 42 Israelis, mostly students. He killed only five, a consequence of bad tactics and limited ordinance. Nukes make the problems of logistics much simpler for mass killers.

So Obama and Clinton are applauding the progress of Iran on a marked highway to nuclear weapons. Thy cheer this as an improvement over the haphazard back roads the mullahs have been imperfectly traveling. It isn't an improvement. It is a disaster. It is an unimaginable carnage just over the horizon that only the intentionally dense or the unbelievably naive cannot foresee.

The Wendy Shermans and the Ernest Monizes and all the rest: the foreign policy equivalent of time-share buyers of Acapulco deals. No doubt they are the smartest kids on the block. Sherman has experience after all — with North Korea and its 1994 fraud on America. Weary realists all, now off to the Vineyard to discuss the hoped-for-change in a regime that hasn't changed a bit since 1979.

Maj. Gen. Qasem Soleimani is laughing. He has won. Ayatollah Ruhollah Khomeini has won from beyond the grave. The clock is ticking and the bright light is coming. Thank you President Obama, Secretary Kerry and Secretary Clinton. Sen. Schumer, your "courage" will not be forgotten either.

Hugh Hewitt is a nationally syndicated talk radio host, law professor at Chapman University's Fowler School of Law, and author, most recently of The Queen: The Epic Ambition of Hillary and the Coming of a Second "Clinton Era." He posts daily at HughHewitt.com and is on Twitter @hughhewitt.