Iran's offer of negotiation over a prisoner swap was not welcomed by the United States because it seeks comprehensive talks covering all areas of dispute, according to an analyst.
"They do not want to negotiate with Iran in separate packages, but want to put all issues in one package and negotiate within that framework," Mehdi Zakerian, an expert on international affairs, said in an interview with ISNA.
Tensions heightened between Iran and the US after Washington walked away from the 2015 nuclear deal (formally known as the Joint Comprehensive Plan of Action) last year and reimposed harsh sanctions.
US President Donald Trump argued that JCPOA was "defective at its core" and that Iran had to come to the negotiating table once again for talks on all issues, including Tehran's missile program and regional activity.
Iran has refused to renegotiate a deal to which all other parties have remained committed, saying talks are only possible if the US lifts its pressure and apologizes.
In a recent visit to New York, however, Foreign Minister Mohammed Javad Zarif offered to negotiate prisoner swaps with Washington.
The US rejected the offer, calling on Iran one-sidedly to show "seriousness" regarding consular issues by releasing imprisoned Americans immediately.
"We call on Iran to free all unjustly detained and missing US persons, including Xiyue Wang, Robert Levinson, Siamak Namazi and Nizar Zakka, among others," the US State Department said.
According to Zakerian, the reason for the rejection is the US administration's refusal to discuss issues separately.
"That was the very problem they had with JCPOA. They saw it as [a deal addressing] one of all issues they have with Iran," he said.
Some analysts have interpreted Zarif's offer as an attempt to lay the groundwork for broader dialogue with the US.
Zakerian rejected the theory, saying this "classic" method would have worked 30 years ago, but is not effective today.
"Today, one cannot use the release of prisoners as a tool for [starting] dialogue," he said.
