Iran and six world powers are in Vienna for the first round of talks on a long-term agreement to limit Tehran's controversial nuclear program.  Both the United States and Iran are already tamping down expectations of any breakthrough like the temporary deal reached late last year.

Iran’s supreme leader, Ayatollah Ali Khamenei said the nuclear session will “lead nowhere,” and he should know – he has the final say on all matters of state in Iran.

“I’m not optimistic about the nuclear talks, but not opposed to them either,” Khamenei said, according to Iranian media.  “What our officials started will continue.  We will not renege.  I have no opposition.”

Later, a senior American official also played down any hope of progress, telling a Reuters reporter that the talks will be a “complicated, difficult and lengthy process” and it’s “probably as likely that we won't get an agreement as it is that we will.”

The two sides have given themselves until 19 July to find a comprehensive solution.