After two years of negotiations and several missed deadlines, the United States and five other world powers struck a historic deal with Iran yesterday that has sharply divided opinion around the globe.
While some saw it as a landmark achievement in international diplomacy, others called it a reckless move that will pave the way for Iran to acquire a nuclear bomb.
At its core, the accord reached after an 18-day marathon session in Vienna lifts longstanding economic sanctions on Iran in exchange for limits on its nuclear programme. The P5+1 group, comprising the five permanent members of the United Nations Security Council and Germany, argue that the deal is the best way to keep Iran away from nuclear weapons.
The US, for instance, maintains it just wants to rein in Iran's nuclear ability enough so it will take at least a year to develop a bomb once restrictions are removed. As for Iran, it has been eager to get some relief from the crippling sanctions.
Yesterday, both sides held up the deal as a game-changer.
Said President Barack Obama: "Today, after two years of negotiations, the United States, together with our international partners, has achieved something that decades of animosity has not: a comprehensive, long-term deal with Iran that will prevent it from obtaining a nuclear weapon."
Similarly, European Union foreign policy chief Federica Mogherini said the deal showed that diplomacy can "overcome decades of tensions and confrontations".
Iranian President Hassan Rouhani, who reached out for negotiations after he was elected in 2013, said it resolved an "unnecessary crisis". "Iran will never seek a nuclear weapon," he said.
Still, Iran's neighbours such as Israel and Saudi Arabia worry that the agreement does not do enough to curb Iran's nuclear ambitions while giving it access to billions of dollars through sanctions relief.
They object to provisions that allow Iran to keep much of its civilian nuclear infrastructure, and the gradual lifting of a United Nations embargo that blocks Iran from buying and selling weapons.
Israeli Prime Minister Benjamin Netanyahu, one of the most vocal critics, condemned the accord as "a historic mistake".
"Iran will receive hundreds of billions of dollars with which it can fuel its terror machine and its expansion and aggression," he said.
The deal will face significant resistance from the Republican-led US Congress. Lawmakers have 60 days to review the deal before a vote in September.
Mr Obama, for whom the deal will be one of his defining foreign policy achievements, has said he would veto any objection. The only way Republicans can scupper the accord is to rope in enough Democrats to go along with them. A two-thirds majority is needed to override a presidential veto.