Washington, May 7 (IANS): A US State Department official said Washington and Tehran could achieve a mutual return to compliance with the 2015 Iranian nuclear deal in the coming weeks if the Islamic Republic makes a "political decision".

The official said in a phone briefing on Thursday that the last three rounds of indirect talks between the US and Iran in Vienna "helped crystallise the choices", but noting "nothing has been agreed" on how to revive the nuclear deal, formally known as the Joint Comprehensive Plan of Action (JCPOA), reports Xinhua news agency.

"If Iran makes the political decision that it genuinely wants to return to the JCPOA as the JCPOA was negotiated, then it could be done relatively quickly and implementation could be relatively swift," the official told reporters.

"But we don't know if Iran has made that decision. There's still a lot of work to do in terms of agreeing on the sanctions, nuclear steps, but also the sequencing and the timetable for implementation of the steps that both sides are going to need to take," he said.

The official suggested that it is possible for Washington and Tehran to achieve a mutual return to compliance in the next few weeks, while stressing "this is ultimately a matter of a political decision that needs to be made in Iran".

The US delegation will return to Vienna this week for a new round of indirect talks with Iran.

"We just have to see whether the next round actually moves things forward, or whether we still are faced with unrealistic demands by Iran," said the official.

Abbas Araqchi, Iran's senior negotiator in Vienna talks, said last week that negotiating parties have reached "common ground in many cases", but there were still differences.

Iranian President Hassan Rouhani said on Wednesday that the US knows that it has to return to law and assume its obligations pertaining to the nuclear deal.

The JCPOA was reached in 2015 between Iran and the P5+1 (the five permanent members of the UN Security Council -- the US, the UK, Russia, France, China, plus Germany) together with the European Union.

Tehran agreed to roll back parts of its nuclear weapons program in exchange for decreased economic sanctions.

Iran gradually stopped implementing parts of its commitments in May 2019, one year after the administration of former US President Donald Trump unilaterally abandoned the agreement and re-imposed sanctions on Tehran.