The Iran nuclear deal is now sealed . from Washington’s end. But since this has been one of America’s most important foreign policy shifts in the last four decades, it’s worth looking back and grading the performance of the key players.

Iran’s supreme leader, Ayatollah Ali Khamenei. Grade: A.

His prediction last week that Israel won’t be around in “25 years” was perfectly timed to complicate President Obama’s effort to get the deal through Congress. Khamenei is a bad guy. When I asked a Middle East expert friend to explain Khamenei’s behavior, he invoked a Yiddish curse on the Iranian: “May all his teeth fall out, except the ones that hurt.”

But he’s also a clever guy. Through this deal Khamenei gets Iran out from under crippling sanctions, which his people want, by pushing the breakout time for Iran to make a nuclear bomb from two months to a year . for 15 years . but getting the world to bless Iran’s “peaceful” nuclear enrichment program, even though it cheated its way there. And he’s done it all while giving his hard-line base the feeling that he’s still actually against this deal and his negotiators the feeling that he’s for it. So all his options are open, depending on how the deal goes.

Hat’s off, Ali, you’re good. When I sell my house, could I give you a call?

But here’s a note to his parents: “Ali got an A, but he has a tendency to get cocky. He is confident that he can pull off this deal without any transformation in Iran’s domestic politics. I suggest you buy him a good biography of Mikhail Gorbachev.”

Dick Cheney. Grade: F.

I cite Cheney because his opposition to the deal, which he’s been peddling along with a new book, was utterly dishonest, but in a way that summed up much of the knee-jerk Republican opposition: This is a bad deal because Obama was a wimp.

No, this deal is what it is because it reflects the balance of power, and the key factor in that balance is that the Iranians came to believe America would never use force to eliminate their nuclear program. But that’s not all on Obama. Republicans, and Cheney personally, played a big role in the loss of U.S. credibility to threaten Iran with force.

After briefing Congress on Sept. 10, 2007, Gen. David Petraeus told Fox News that Iran was supporting and directing Iraqi Shiite insurgents who have “carried out violent acts against our forces, Iraqi forces and innocent civilians.” Iran was cited for making specially shaped roadside bombs responsible for killing hundreds of U.S. troops. Yet, even though our commanders said that publicly, their bosses . George W. Bush and Dick Cheney . refused to ever order retaliation against Iranian targets. Iran noticed.

Ditto on nukes. As Peter Beinart wrote for The Atlantic last week, Cheney stopped by “Fox News Sunday” to bash Obama’s nuclear deal, “but moderator Chris Wallace, to his credit, wanted to ask Cheney about his own failings on Iran. On the Bush administration’s watch, Wallace noted, Iran’s centrifuges for enriching uranium ‘went from zero to 5,000.’ Cheney protested, declaring that, ‘That happened on Obama’s watch and not on our watch.’ But Wallace held his ground. ‘No, no, no,’ he insisted. ‘By 2009, they were at 5,000.’ Cheney paused for an instant, muttered, ‘right,’ and went back to his talking points.”

Note to his parents: “Dick has a problem telling the truth, and he’s not alone. Some G.O.P. critiques of this deal should be looked at, but they’ll never be taken seriously if the party isn’t straight about its own role in our loss of deterrence vis-a-vis Iran.”Israel’s Prime Minister Benjamin Netanyahu: Grade C.

No one had more impact in getting the world to impose sanctions and take Iran’s nuclear threat seriously than Netanyahu. But his reckless spat with Obama, which went beyond substance to openly endorsing Obama’s G.O.P. rivals and colluding with G.O.P. House leaders to address Congress . without the president’s support . hurt him, Israel and the deal.

Had Bibi hugged Obama, he could have made Israel effectively the sixth party in the P-5 side of negotiations with Iran and stiffened every spine. Instead, Netanyahu marginalized Israel. And by calling elections in the middle of it all, and forming a far-right cabinet with extremist Jewish settlers, Netanyahu is playing right into Iran’s hands: Iran wants a one-state solution, where Israel never leaves the West Bank and is in permanent conflict with Palestinians and Muslims, so Iran can better delegitimize and isolate Israel.

Note to Netanyahu’s parents: “Bibi won’t be punished for any of his mistakes; domestic U.S. politics will ensure that. But beware: That will only increase the odds that he’ll lead Israel into a permanent, corrosive occupation of the West Bank, make support for Israel an increasingly Republican cause and lose the next generation of American Jews.”President Obama. Grade: I (Incomplete).

Note to Obama’s parents: “This deal makes sense; it can keep Iran away from a bomb. But Barack should go to bed every night for the next 15 years worrying whether Iran is living up to it. That’s the best way to ensure that he, his party and his successors will stay vigilant and put in place an effective deterrence to Iran ever building a bomb. I hope he gets an A, but only history can give it to him.”