Tehran, July 13, IRNA - The Iranian foreign minister at the center of high-stakes negotiations over the nation's nuclear program spent the better part of the 1980s mastering international studies in Denver.

Mohammad Javad Zarif, Iran's top diplomat since 2013, earned his master's degree and Ph.D. in international studies at the University of Denver's Graduate School of International Studies � now known as the Josef Korbel School � in 1984 and 1988, respectively.

Even then, Zarif's professors say he stood out for his intellect, discipline and optimism.

'He was among the very best students that I've ever taught,' said Tom Rowe, a professor at the graduate school who led the committee that oversaw Zarif's dissertation. 'He's just a very nice person.'

Zarif, who completed his undergraduate education at San Francisco State University, was at DU when international students made up about half of the Ph.D. program, professors said. He was in Denver during the Iran-Iraq War, a nearly decade-long conflict that left more than 100,000 Iranians dead. That conflict deepened his interest in international law and diplomacy, Rowe said.

Zarif also was filled with hope.

Karen Feste, a professor at the school who taught Zarif in two classes, remembered an exchange he once had with another student. Zarif and the other student were debating and could not reach agreement.

'I said, 'Well, does that mean paralysis and there's nowhere to go?'' Feste remembered interjecting. Zarif's response, Feste recalled: 'There's always hope. You have to have hope.'

As he works with U.S. Secretary of State John Kerry, Zarif continues to remain optimistic even as deadlines pass. On Thursday after a tense session, Zarif tweeted: 'We're working hard, but not rushed, to get the job done. Mark my words; you can't change horses in the middle of a stream.'

On Sunday, The Associated Press reported that a deal had been reached and would be unveiled Monday.

'He really believes in hope. He really believes in possibilities,' Feste said. 'Of course we're very proud that he's risen to this position.'

'I'm very pleased and enthusiastic that he's able to play this role,' Rowe said. 'It's difficult for me to see anyone who could do a better job at trying to bring this about.'

By IRNA