Here is an explainer of developments in Iran’s nuclear program going back to 1957.

1957
Iran’s nuclear program began in 1957, ironically, with the help of the United States. The two countries signed a cooperation agreement. And the U.S. began leasing enriched uranium to Iran.

1958
A year later, Iran joined the International Atomic Energy Agency, the IAEA.

1968
A decade later, Iran signed on to two treaties including the Nuclear Non-Proliferation Treaty. That’s the agreement meant to prevent the spread of nuclear weapons.

1975
By 1975, Iran had agreed to allow IAEA inspectors into the country to ensure its nuclear development was peaceful. That year, the United States said it supported Iran’s “full-fledged” nuclear power development.

1979
Then came the Islamic Revolution in 1979. The United States stopped supplying highly enriched uranium to Iran. In the decades that followed, Iran would sign agreements with other nations, including Russia.

1998
Fast forward to 1998.
U.S. President Bill Clinton linked Iran’s nuclear development to a possible weapons program. He would go on to sign a law… imposing sanctions on organizations or individuals which helped Iran’s nuclear program. At the same time, Iran boosted its nuclear cooperation with Russia.

2003
In 2003, the IAEA accused Iran of concealing its nuclear activities. Iran insisted it had no intent to pursue atomic bombs.

2006
Tensions rose for the next several years. And in 2006, the IAEA referred Iran’s nuclear program to the United Nations Security Council. Tehran responded by formally suspending all international inspections.

2012
Then came a series of assassinations of high-level nuclear scientists in Iran. And in 2012, a virus attack… known as “Stuxnet”… took a key Iranian enrichment facility offline. That same year, Israeli President Benjamin Netanyahu made his memorable speech to the United Nations, railing against Iran. (this is the speech where he drew the red line on the bomb)

2013
More Western sanctions would follow. So, too, would an interim agreement in 2013 between Iran and the permanent members of the U.N. Security Council.

2015
Discussions continued and then, in 2015, a breakthrough. Both sides reached the framework for a nuclear deal.
The West would agree to lift sanctions on Iran, if Iran would agree to significantly restrict and reduce its uranium enrichment programs.

Those talks ended with a final deal.