World powers and Iran have formally announced a comprehensive nuclear accord.
Federica Mogherini, the European Union's foreign policy chief, said: "Today is an historic day."
She added that it was a great honour "for us to announce that we have reached an agreement on the Iranian nuclear issue".
Iran's Supreme Leader has given a cautious welcome to the country's historic nuclear deal, but warned the text should be "carefully scrutinised" and claiming some of the other nations involved are "not trustworthy".
In a letter - his first public statement on the agreement - he thanked President Hassan Rouhani for the "significant step", but warned: "The text of the deal should be carefully scrutinised and the legal procedures should be taken so when the deal is ratified the other side cannot breach it."
Under the deal, sanctions will be lifted on Iran in exchange for an agreement of long-term curbs on its nuclear programme.
Khamenei is the ultimate authority on all matters of state, but was not directly involved the negotiations.
The P+1 nations that agreed the deal with Iran are China, France, Russia, the United Kingdom and the United States.
Prime minister Netanyahu has likened the nuclear deal with Iran to the unsuccessful 1994 deal on North Korea's nuclear programme.
An end to Iranian nuclear question could soon be a reality after years of hard and often tense negotiations.