Iran agreed Monday to allow inspectors from the International Atomic Energy Agency (IAEA) into two key nuclear sites, which were previously kept hidden.
The Gchine uranium mine and a heavy-water reactor in Arak will be opened up to inspectors after Ali Akbar Salehi, the head of Iran's atomic energy organization, and IAEA chief Yukiya Amano met in Tehran, according to the Guardian.
Iran and the IAEA released a joint statement, saying, "Iran's cooperation will include providing the IAEA with timely information about its nuclear facilities and in regard to the implementation of transparency measures."
The news on Iran's nuclear sites comes after weekend talks in Geneva ended with no agreement on Tehran's nuclear program.
More from GlobalPost: Iran nuclear talks: No deal this time
Kerry insisted that the P5 + 1 (the United States, China, Britain, France, Russia and Germany) were united behind a draft proposal that seeks to halt Iran from building a nuclear weapon in exchange for lifting sanctions.
Earlier reports suggested that France had scuttled the deal at the final hour as it did not go far enough in preventing Iran from acquiring a nuclear weapon.
"The French signed off on it, we signed off on it," Kerry said on Monday. "There was unity but Iran couldn't take it."
Some US lawmakers said on Sunday that they wished to tighten sanctions on Iran before a deal was made. Reuters reported that the US Senate Foreign Relations Committee would push for additional sanctions this week in order to put pressure on Iran.
There is a widespread fear among the Congress that the US will agree to a deal that does not halt Iran's nuclear ambitions.
Britain's Foreign Secretary William Hague echoed the sentiment when speaking to British parliament Monday.
"It's very important for the Iranian authorities to understand that the pressure will be there for greater sanctions, for an intensification of sanctions, unless an agreement is reached on these matters," he said.
Israel has also lobbied hard not to accept any deal that does not compeletely stop the enrichment of uranium in Iran. Kerry responded to Israeli Prime Minister Benjamin Netanyahu's criticism of the deal, calling it premature.
"The time to oppose it is when you see what it is, not to oppose the effort to find out what is possible," Kerry said Monday.
The US ambassador to Israel, Dan Shapiro, sought to reassure Israelis Monday, saying the US and Israel shared "an identical agenda."
Shapiro added that President Barack Obama had made it clear that "he will not permit Iran to acquire a nuclear weapon, period, and is prepared to use all elements of our national power to ensure that we are successful."
Talks between the great powers and Iran are set to resume next week.