WASHINGTON - The US State Department on Thursday repeated that there has been progress in talks about resuming compliance with the Iran nuclear deal but that challenges remain, saying it has no time frame for an end to the sixth round of talks underway in Vienna.

"We have been able to achieve some progress but challenges remain," State Department spokesman Ned Price told reporters in a telephone briefing. "I don't have a time frame for the sixth round of talks," he said when asked how long the current round of indirect negotiations might last.

Reuters