esfera/Shutterstock Save for later Print Download Share LinkedIn Twitter The seventh round of negotiations between world powers and Iran aimed at reviving the 2015 nuclear deal ended Friday on a decidedly sour note, leaving confusion as to what happens next. Members of the US negotiating team were set to head back to Washington Friday, although other parties to the deal said they would resume talks next week.“The seventh round of talks did end today in Vienna. [US] Special Envoy [Rob] Malley and his interagency team are returning to Washington now," said White House spokesperson Jen Psaki late Friday afternoon.Russian Ambassador Mikhail Ulyanov described it as a "technical break" and said the talks, which began on Nov. 29, would continue next week. "An opportunity for each participant, including Iran and the US, to consult with the capitals and to think how to proceed further, taking into account the positions of other counterparts," he tweeted.The talks are aimed at easing sanctions on Iran’s economy in return for controls over the country’s nuclear program, in line with the 2015 Joint Comprehensive Plan of Action, which the US had abandoned under former President Donald Trump.Iran’s oil exports remain severely limited by the economic sanctions.These were the first negotiations since hard-line Iranian President Ebrahim Raisi took office in August.US Losing Patience US Secretary of State Antony Blinken indicated US patience is wearing thin, saying Iran’s negotiators did “not seem to be serious about doing what’s necessary to return to compliance, which is why we ended this round of talks in Vienna.”US officials have been warning for months that Iran’s nuclear program could develop to a point beyond which it could be constrained by the 2015 agreement. Since the US walked away from that deal, Tehran has continued developing key technologies such as uranium enrichment. The concern is that Iran’s technological advances could soon put out of reach the roughly one-year "breakout period" to obtain the material for a nuclear weapon envisioned in the original deal.Tight Window“The window is very, very tight because what is not acceptable and what we will not allow to happen is for Iran to try and drag out this process while continuing to move forward inexorably in building up its [nuclear] programs,” Blinken said at a Reuters virtual conference Friday afternoon. European diplomats accused Iran of demanding "major changes" to a painstakingly drafted text they said was nearly completed earlier this year. In a statement, senior officials from France, Germany and the UK said it is "unclear how these new gaps can be closed in a realistic time frame."