As details emerged of the interim agreement reached between six world powers and Iran over principles for rolling back its nuclear program, the question on everyone's mind is which way did the scales tip?

While Obama acknowledged a formal agreement won't be signed until June, ABC News breaks down the essential elements of who got what at the end of the eight-day marathon negotiations in Switzerland. THE UNITED STATES

A Cut Back in Centrifuges

One of the primary concerns over Iran's nuclear programme was its amassing of centrifuges, which can be used to enrich uranium into the material needed to make an atomic bomb.

According to the parameters of the deal, Iran has agreed to reduce by two-thirds its currently installed centrifuges. The 19,000 installed today would be cut to no more than 6,104 for the next 10 years. The 13,000 decommissioned centrifuges will be sent to monitored storage by the International Atomic Energy Agency (IAEA).

Iran also has agreed not to build any new nuclear enrichment facilities for the next 15 years.

The "Breakout” Time

Right now Iran's "breakout time," or the time it needs to actually produce a bomb, is two to three months.

Under the new agreement, the timeline will be extended to one year over the next 10 years.

Stockpile of Nuclear Material

Iran will have to reduce its current stockpile of 10,000 kg of low-enriched uranium to 300 kg over the next 15 years, according to the deal.

That uranium will also not be allowed to be enriched over 3.67 percent. That's a level at which nuclear power reactors can operate, but much lower than what is considered "bombgrade" enrichment of around 90 percent.

Inspections and Verification

As Obama said in his Rose Garden speech after the announcement of the framework, "If Iran cheats, the world will know it."

The way the world will find out about that cheating? An extensive number of inspections. The framework agreement stipulates that no easing in sanctions of any kind can begin until Iran submits to inspections and verifies that it has dismantled its nuclear programme.

According to Secretary of State John Kerry, Iran has agreed to allow the IAEA to "investigate any suspicious site or any allegations of covert nuclear activities anywhere."

The agreement stipulates that IAEA inspectors will have "regular access" to

any of Iran's nuclear facilities as well as the supply chain that contributes to its program.

IRAN

Sanctions Relief

Iran's primary incentive for engaging the West in nuclear talks was to lift crippling economic sanctions levied by the US, European Union and the United Nations. Many, but not all of those sanctions, would be lifted as soon as Iran proves it is submitting to the process.

For years, these sanctions have put severe pressure on Iran's economy and

isolated it from the international community. At a time when Iranians are unable to even use a credit card, the economic benefits could prove to be immense.

Research and Development

Under the agreement Iran would be allowed to continue nuclear research and development, a practice critics of the deal say could be used to research sophisticated nuclear reactors that could eventually be put to use in any plans to develop a bomb.

Deep Buried Reactor at Fordow

Although the tentative agreement says Iran will no longer be allowed to enrich uranium at its deep-buried nuclear facility at Fordow, Iran will be allowed to keep the facility open. That's seen by critics as a concession by the US, which ultimately would like to have seen the facility shuttered. Iranian's negotiators will surely present this portion of the agreement as a victory for Tehran.

FINAL TAKEAWAY

Some Republicans have already vowed to derail the deal.

In an interview with ABC News, Sen. Tom Cotton, R-Arkansas, said the deal was "only a list of very dangerous US concessions that will put Iran on the path to a nuclear weapon."

“I plan to work with all of my colleagues on both sides of the aisle who have already expressed disquiet about terms such as these, to stop this deal from going forward, to keep America safe, and to prevent a nuclear arms race in the Middle East,” Cotton said.

In Tehran, reports indicate Iranian citizens have taken to the streets to celebrate the conclusion of the talks and the proposed lifting of sanctions.