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Iran and six world powers agreed Friday to extend talks over Tehran’s nuclear program until Nov. 24.

In a statement released Friday night, Secretary of State John Kerry, who flew into Vienna a week ago to try and advance the talks, said, “it is clear to me that we have made tangible progress in our comprehensive negotiations, but there are very real gaps in some areas… diplomacy takes time, and persistence is needed to determine whether we can achieve our objectives peacefully.”

Consequently, Kerry said, “we have decided - along with the EU, our P5+1 partners, and Iran - to extend the Joint Plan of Action until November 24, exactly one year since we finalized the first step agreement in Geneva.

“This will give us a short amount of additional time to continue working to conclude a comprehensive agreement.”

Iran's nuclear program will remain halted during the next four months, Kerry said, and “in return, we will continue to suspend the sanctions we agreed to under the JPOA and will allow Iran access to $2.8 billion dollars of its restricted assets.”

The decision had been expected, with much of Friday spent on debating not obstacles standing in the way of an agreement but how long the add-on talks should go on and other related details.

The biggest obstacle is uranium enrichment, which can make both reactor fuel and the core of a nuclear warhead. Iran says it does not want such weapons but demands it be allowed to keep its present program. The United States and its Western allies want deep cuts.

The Associated Press contributed to this story