World leaders hailed the Iran nuclear deal on Tuesday, with Barack Obama envisioning a "new direction" and Vladimir Putin voicing a global "huge sigh of relief" -- though Israel criticised it as a "historic mistake".
Major international powers who thrashed out the agreement with Tehran said they hoped Iran would build on the opportunity to come in from the cold.
However, Israeli Prime Minister Benjamin Netanyahu hinted he remained ready to order military action against Iranian nuclear sites.
US President Obama said the agreement vindicated the exhausting diplomatic efforts and offered a chance to reset vexed relations with Tehran.
"We have stopped the spread of nuclear weapons in this region," he said.
"Every pathway to a nuclear weapon is cut off.
"This deal offers an opportunity to move in a new direction. We should seize it."
But should Iran step back from measures in the agreement, all sanctions "will snap back into place", Obama warned.
He noted the "real" differences between Iran and the United States, adding that the deal was based on verification, not trust.
Sealed in Vienna after a 13-year stand-off, the deal was reached between Tehran and the United States, Russia, China, Britain, France and Germany.
Russian President Vladimir Putin hailed the deal as a "firm choice for stability and cooperation".
"The world has breathed a huge sigh of relief," he said.
Putin said Moscow would "do everything in its power" to ensure the agreement worked.
Russian Foreign Minister Sergei Lavrov said the deal would "make the situation in the Middle East healthier".
He added: "We have great plans to develop Iran's nuclear energy," referring to Russia's plans to build more power reactors in the country.
Low-enriched uranium will also be brought from Iran to Russia.
The Vienna agreement is aimed at ensuring Iran does not obtain a nuclear bomb, opening up Tehran's sanctions-stricken economy and potentially ending decades of bad blood with the West.
Iran has always denied Western accusations that it has been trying to acquire the know-how to make nuclear weapons.
Netanyahu called the deal a "historic mistake".
"In every area where it was supposed to prevent Iran attaining nuclear arms capability, there were huge compromises," he said.
"We did commit to preventing Iran from acquiring nuclear weapons, and this commitment still stands," he added, in what was seen as a thinly veiled threat of pre-emptive strikes against Iranian nuclear sites.
Through sanctions easing, "Iran will get hundreds of billions of dollars with which it will be able to fuel its terror machine," Netanyahu added.
United Nations Secretary General Ban Ki-moon said the agreement could help bring peace across wider region.
"I hope -- and indeed believe -- that this agreement will lead to greater mutual understanding and cooperation on the many serious security challenges in the Middle East," he said.
"As such, it could serve as a vital contribution to peace and stability both in the region and beyond."
British Prime Minister David Cameron said the deal would help "make our world a safer place" and said Iran now had a "real opportunity" to benefit from the pact economically.
However, "this agreement will not solve all the difficulties, especially between Iran and its neighbours," he said.
"We will continue to work with our partners in the region to ensure stability and security and I hope that Iran will also follow this path."
French President Francois Hollande said "the world is making headway", and urged Tehran to now help world powers end the Syrian conflict.
"Now that Iran will have bigger financial capabilities -- as there will no longer be sanctions -- we must be extremely vigilant on what Iran will be," he added.
"Iran must show... that it is ready to help us on Syria to end this conflict."
Syria's President Bashar al-Assad said his key ally Iran had "achieved a historic victory" with the agreement.
He congratulated Iran's supreme leader Ayatollah Ali Khamenei on a "major turning point in the history of Iran, the region and the world".
Iran's eastern neighbours were also cheered by the deal.
Afghanistan said it welcomed efforts aimed at "strengthening of peace and stability in the region", while Pakistan said that confidence-building measures over Iran's nuclear programme "auger well for peace and security in our region".
Former Swedish prime minister Carl Bildt suggested the 2015 Nobel Peace Prize should go to the negotiators.