- "Today marks an important milestone toward preventing Iran from obtaining a nuclear weapon," says President Barack Obama
- Iran will not go out Sunday and wind down its centrifuges enriching nuclear fuel, and sanctions won't fall
- But the administration, legal and bureaucratic work necessary for that to happen kicks off
(CNN)It's Sunday, October 18, the day the Iran nuclear deal gets rolling.
"Adoption Day" for the Joint Comprehensive Plan of Action, as the deal is formally called, means that officials from Iran, the United States and other world powers involved in the deal get started turning it into reality.
But that doesn't mean Iran will go out Sunday and wind down centrifuges enriching nuclear fuel or that Western nations will remove the millstone of economic sanctions around Iran's neck.
All of that could take a decade, in total, of checking off long lists of compliance.
For anything real to happen, a lot of legislative procedure, administration and bureaucracy must come first, and that kicks off on Adoption Day.
Here are some things to expect now and in the future as the Iran deal passes complex milestones designated as particular "Days."
Why October 18?
The JCPOA stipulates that Adoption Day be 90 days after Finalization Day, which was the day the U.N. Security Council endorsed the deal after all the negotiating parties -- Iran, the United States, Germany, France, Britain, China and Russia, as well as the European Union -- agreed to it.
The Security Council adopted a resolution to endorse the deal on July 20. Count forward 90 days, and you get Sunday, October 18.
What will Iran do?
Iran will tell the International Atomic Energy Agency that, on a future date, Tehran will apply the Additional Protocol, according to the JCPOA. That's a legal document that gives nuclear inspectors added authority to check up on Iran's obligations that are designed to prevent it from working toward a nuclear weapon.
That future date is Implementation Day -- yet another milestone in the agreement, and the big one, when parties are satisfied that Iran has made adjustments to its nuclear program and the West eases off of sanctions.
"Implementation Day will not happen until Iran complies with all steps under JCPOA," a U.S. official told reporters on a conference call late Saturday.
Starting Sunday, Iran will also help the IAEA clarify past and current concerns about its nuclear program.
What will the United States do?
President Barack Obama will issue waivers on sanctions. They won't be good until Implementation Day, but they will address Iran's oil sales and transportation and banking industries, among others.
The President will also address the future lifting of other sanctions.
"Today marks an important milestone toward preventing Iran from obtaining a nuclear weapon and ensuring its nuclear program is exclusively peaceful going forward," Obama said in a statement Sunday.
The White House, Tehran and the European Union will also confer on how to announce things to the world. Past talk of lifting sanctions on Iran has set off heated opposition in the U.S. Congress.
Republican presidential contender Donald Trump piled on when the deal was ratified, saying he would have added sanctions in the deal. But he and fellow Republican candidate Jeb Bush have said they would not tear up the JCPOA.
And Israeli Prime Minister Benjamin Netanyahu has railed against the deal in the past, even traveling to Washington to beseech Congress to reject it, for fear it could lead to Iran acquiring an atomic bomb.
Apropos of bad PR: Iran ruffled feathers with a missile test a week ago that may have violated a U.N. resolution.
A few days later, it showed off video of cavernous underground missile silos.
None of that violated the nuclear agreement, but it spread unease just before Adoption Day.
What will other parties to the deal do?
The European Union will adopt a regulation to terminate sanctions related to Iran's nuclear program. But again, it wouldn't take effect until that all-important Implementation Day.
The EU countries that helped hammer out the nuclear deal will start work with Iran on a document that defines specific joint responsibilities including changes to Iran's Arak Heavy Water Reactor.
Some have feared that Arak could produce a lot of bomb-grade plutonium in a short period of time.
China will play an important role in making such technical adjustments, a Washington official told reporters.
What other 'Days' are to come?
After Adoption Day, Implementation Day is the next milestone; then come Transition Day and UNSCR Termination Day.
- Implementation Day marks Iran's concrete tackling of banned changes to its nuclear program, and the beginning of the end for sanctions. Some can be reimposed, should Iran dodge compliance.
- Transition Day is eight years from Adoption Day -- or it could come earlier, if "the IAEA has reached the Broader Conclusion that all nuclear material in Iran remains in peaceful activities," as the deal states. A U.S. official stressed to journalists that speed of compliance is nice, but secondary. Washington is "more worried that it's done right, than if it's done quickly." Transition Day also means even more of the many, many sanctions would fall.
- And finally, 10 years from now, UNSCR Termination Day would roll around. The abbreviation stands for U.N. Security Council resolution -- the one that was passed on Finalization Day endorsing the Iran nuclear deal.
That "Day" would mark the end of the long process to create trust through verification of the peaceful nature of Iran's program, and virtually all remaining sanctions would fall.
But some obligations from the agreement would continue.
What does the future hold?
If things work out, maybe an Iran without nuclear weapons that is more prosperous and eager to trade with the rest of the world. Britain's Foreign Secretary Philip Hammond was optimistic Sunday that they will.
"This will ensure that a nuclear weapon remains beyond Iran's reach, thus creating a safer region while opening opportunities for Iran to re-engage with the international community as sanctions are progressively lifted," he said in a statement.
U.S. Secretary of State John Kerry was more measured.
"If fully implemented, it will bring unprecedented insight and accountability to Iran's nuclear program forever. As we move from Adoption Day now towards Implementation Day, I and my entire team will remain vigilant and mindful of not just how far we have come, but how much further we have to go in seeing that this deal is fully implemented," he said in a statement.
If things don't work out?
Proponents of the deal say that even in a bad scenario, the JCPOA would give the United States proper justification, and some lead time, to carry out tough actions.
Critics fear the worst if compliance goes south: a financially better-off Iran supporting regional terrorism and armed with a nuclear arsenal.