The US State Department commented on the progress of negotiations with Iran on the JCPOA

"There was modest progress last week, we expect to strengthen it this week," RIA Novosti Price quoted as saying.

He noted that it is in the interests of the United States that "it remains to achieve a joint return to the JCPOA," which is impossible if Iran continues to take steps to develop its nuclear program.

Price said Washington believes Iran "should seriously consider" the negotiation process.

Earlier, Russia's permanent representative to international organizations in Vienna, Mikhail Ulyanov, said about "undeniable progress" in the negotiations on the JCPOA.

On December 27, the heads of the Russian and US delegations met before the start of the eighth round of consultations on the restoration of the Iranian nuclear deal.