The Iran deal: can an agreement with Iran stop it from building a nuclear weapon?

• Author: Brown, Bryan
• Position: INTERNATIONAL

Last month, the U.S. and five other nations reached a preliminary deal with Iran to limit its nuclear program in exchange for the lifting of economic sanctions that have crippled its economy. The U.S., its allies, and the U.N. believe Iran has been secretly trying to develop nuclear weapons; Iran says it's only interested in peaceful uses of nuclear technology, like producing electricity.

The negotiations, which began in 2013, were so difficult that they often threatened to collapse. Negotiators still have a lot of tough issues to hammer out by June 30, the deadline for a final accord. And deep suspicion between Iran and the U.S. could still kill the agreement. Here's what you need to know about the deal.

Why is Iran's nuclear program a threat?

Iran, which is controlled by hard-line Muslim clerics, has repeatedly threatened the U.S. and its allies. Since Iran's 1979 Islamic revolution, its leaders have condemned the U.S. as "the Great Satan" and called for its downfall.

Israel is especially fearful of Iran having nuclear weapons. Iran not only denies Israel's right to exist, it has called for the Jewish state to be "annihilated."

Iran has long been a destabilizing force in the Middle East. It sponsors terrorist groups like Hezbollah in Lebanon and Hamas in Gaza.

Another worry is that a nuclear-armed Iran could start a regional arms race: Saudi Arabia, another major U.S. ally threatened by Iran, has warned it may pursue nuclear arms if Iran has them.

What does the preliminary agreement say?

Iran would limit its nuclear capacity so that it has enough nuclear material to generate electricity but not enough for a weapon. Specifically, it would reduce its stockpile of enriched uranium, the key element needed to make a nuclear bomb. It would also cut its total number of centrifuges (the machines that process uranium) by two-thirds. And it would allow international inspectors access to its nuclear sites.

The Western powers have agreed to lift the sanctions that have cut Iran off from international trade and prevented it from selling its oil. Iranian President Hassan Rouhani was elected in 2013 on the promise to end the sanctions and improve relations with the West. But exactly when the sanctions would end could be a big sticking point to a final agreement.

Will the deal keep Iran from producing a bomb?

President Obama says the inspections outlined in the agreement are very robust and will prevent Iran from cheating. He called the deal "our best...