The discussions on Iran's nuclear program took place in Oman, Geneva, as well as New York City during the United Nations General Assembly.
President Barack Obama, who also spoke with Iranian President Hassan Rouhani via telephone in late September, personally authorized the talks, which helped set up higher-level negotiations.
Oman's Sultan Qaboos bin Said, who has acted as an intermediary, hosted the two sides for talks and also made a trip to Iran.
Meeting publicly has been challenging for both countries, ABC News said.
In Iran, anti-American sentiment discouraged politicians from negotiating openly with the united States.
Obama has also been criticized for his willingness to communicate with Iran.
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