President Obama's phone call with Iranian President Hassan Rouhani marks the first time the nations' leaders have communicated directly since 1979. What does this mean for their future relationship? NBC's Chuck Todd reports.

President Barack Obama revealed Friday that he talked with Iranian President Hassan Rouhani, marking the first time leaders from the U.S. and Iran have directly communicated since the 1979 Iranian revolution.

"Just now I spoke on the phone with President Rouhani of the Islamic Republic of Iran," he said from the White House.

Rouhani has been engaged in a publicity blitz as of late, a streak that began with his sit-down with NBC News' Ann Curry last week. Rouhani spent the last few days at the U.N. General Assembly meeting in New York, making a number of public addresses indicating that Iran was open to a deeper relationship with the U.S. and the West, and resolving conflict around his country's nuclear program.

"The two of us discussed our ongoing efforts to reach an agreement over Iran's nuclear program," Obama said. "I reiterated to President Rouhani what I said in New York: While there will surely be important obstacles to moving forward, and success is by no means guaranteed, I believe we can reach a comprehensive agreement."

The president noted that his conversation with Rouhani, which took place as the Iranian president headed to the airport, "underscores the deep mistrust between our countries, but also indicates the prospect of moving on that difficult history."

Moments before Obama took the podium, Rouhani tweeted the news.

In phone convo, President #Rouhani and President @BarackObama expressed their mutual political #will to rapidly solve the #nuclear issue. — Hassan Rouhani (@HassanRouhani) September 27, 2013

A senior administration official said that Obama began the conversation by congratulating Rouhani on his election victory, and noted the constructive statements that Rouhani has made since taking office. The "bulk of the call focused on the nuclear issue," the official said.

The call ended with Rouhani telling Obama in English to "have a nice day" and Obama replying thank you in Farsi.

The White House said the Israeli government and leaders in Congress had been notified of the phone call. Israeli Prime Minister Netanyahu is scheduled to visit the White House on Monday.

The senior official said no further conversations were expected any time soon. The next open forum for this discussion will be in Geneva at the P5+1 nuclear talks in October.

The phone conversation between the U.S. and Iran could change their relationship. NBC's Ann Curry break down what this really could mean

Rouhani's visit to the U.N. was hailed as major progress in U.S.-Iranian relations even before Friday afternoon, but a 30-minute meeting that didn't involve him or Obama at all also contributed to the historic change in the countries' relationship.

On Thursday, Iranian Foreign Minister Javad Zarif and Secretary of State John Kerry held a one-on-one meeting, the first between the U.S. and Iran in a generation. The rare get-together was groundbreaking, according to Iranian analysts.

"The fact that Kerry and Zarif spent about a half an hour together ... as a solo, bilateral, was both unprecedented and very significant for the prospect of future talks for the two sides," said Suzanne Maloney, a fellow in the Saban Center for the Middle East Policy at the Brookings Institute.

The interaction between the U.S. and Iran could affect Syria. NBC's Andrea Mitchell reports.

After the meeting, Kerry said in a statement, "We had a constructive meeting, and I think all of us were pleased that Foreign Minister Zarif came and made a presentation to us, which was very different in tone and very different in the vision that he held out with respect to possibilities of the future."

Aiding the discussions was the fact that this wasn't the first time the two men have met: Zarif was based in New York as Iran's permanent representative to the U.N. from 2002 to 2007, during which time he met a number of senators, including Kerry, and "had a very good rapport" with them, Maloney said.

"What we're potentially seeing is the start of a bilateral channel. Not just in these negotiations among the international community and Iran, but an ongoing dialogue between Washington and Iran on all of the issues of concern between the two governments," she said. "We've had lower level versions of that in the past. If this can be maintained and built upon, it really is the start of something historic."

Still, the path to removing the biggest roadblock between the countries — U.S. economic sanctions on Iran — will be a bumpy one.

"In order to make this process move quickly, as both the U.S. and Iran want, there are going to have to be concessions on both sides," said NBC contributor and Iranian-American author of "The Ayatollahs' Democracy: An Iranian Challenge" Hooman Majd.

Iranians are desperate for a removal of the sanctions, which have devastated their livelihoods, with unemployment and inflation sky-high as a result of them. Ordinary tasks such as banking and getting medicine for sick patients are next to impossible. And Iran's oil output has plummeted, costing the country millions per year.

Historic phone call in the Oval Office: Pres Obama talks w Iran Pres Hassan Rouhani this afternoon pic.twitter.com/5EZSOdBouD — petesouza (@petesouza) September 27, 2013

On Tuesday, Rouhani told the U.N. General Assembly that Iran poses "absolutely no threat to the world" and that the sanctions imposed by the U.S. are "violent — pure and simple" and "intrinsically inhumane."

As his stay at the U.N. wrapped up on Friday, Rouhani had nothing but kind words to say about the United States in a news conference: "The atmosphere is quite different from the past," he said. "Our goal is the shared interest between the two nations. Our goal is resolving problems, our goal is step-by-step creating trust between the governments and peoples."

Obama's conversation with Rouhani comes amid recent conciliatory statements made of late by the Iranian leader, who took office in August.

The possibility of a meeting between Obama and Rouhani was a major cause for speculation during the United Nations General Assembly earlier this week, though no meeting came to pass.

NBC News' Stacey Klein contributed to this report.

This story was originally published on