GWEN IFILL: And for more on today's developments, Margaret joins me from the United Nations now.Margaret, earlier today, the president directed his secretary of state to meet with his counterpart, his Iranian counterpart.

Then we expected and thought there might be a little handshake or a sideline meeting at the United Nations between the two leaders.And, as you just reported, that didn't happen. And now tonight Rouhani issaying perhaps conditionally these meetings might occur.What's really happening?

MARGARET WARNER: Well, what's really happening, Gwen, is that to direct Secretary of State John Kerry to deal directly with the Iranian foreign minister bumps up these talks about Iran's nuclear programto a whole new level.

Now, they will take place within the context of what they call the P5+1, which is the permanent members of the Security Council plus Germany. But these have gone for years, the entire Obama first term, without any real results.

This moves it to a new level, a commitment from the leadership to have their senior diplomats engaged,and some feel also may open the possibility of a direct sort of bilateral conversation between Kerry and Zarif.

The reason is that the Obama administration feels a great sense of urgency to move quickly on this. Rouhani is under big pressure. I mean, he got elected with the promise of pursuing a more moderate course, not out of, you know, a big change of heart on Iran's part, but to get these crippling sanctions eased.

And though Khamenei, the supreme leader, supports him, there is a belief here in the U.S. that he doesn't have long to deliver before hard-liners pounce.And for the United States and Israel, the window isalso closing because Iran has been, as we know, enhancing its capabilities so tremendously -- they have now got 18,000 centrifuges to enrich uranium -- that they are not far from the ability to break out and create a nuclear weapon right under the nose of the international community in such a short time that military action doesn't become feasible.

So the president wants to avoid a kind of rope-a-dope strategy in which the U.S. gets sucked back intoendless negotiations while Iran continues to beef up its capabilities, and bumping this up to the Zarif-Kerry level -- and they will meet for the first time on Thursday at one of these group meetings -- is a real indication of that.

GWEN IFILL: Margaret, as you know as well as anybody, speeches are one thing. Even choreographed handshakes are another, but reality, did reality shift today?

MARGARET WARNER: Well, if perception is reality, yes. Yes.I mean, you had an entire audience of world leaders and the entire world focused on the speeches of these two men. President Obama made clear hewants to pursue a diplomatic track or it's worth testing the diplomatic track.

At the same time, he didn't give up the prospect of military force.And Rouhani was certainly not as bellicose and saber-rattling as his predecessor, Ahmadinejad, used to be at these gatherings, as we all remember, talking about the Holocaust not being real and just a lot of really inflammatory language.

But, that said, talking to senior U.S. officials just now, they didn't see in Rouhani's speech necessarily a great -- you know, there wasn't much leg or ankle shown in this speech. And there certainly wasno specifics about what Iran might be willing to give. They didn't expect that in a speech. I mean, who would negotiate in a speech?

But the attitude of the administration here is, reality may have changed, but that really remains to be demonstrated. And the meeting Friday, while not a true negotiating meeting, will be the first opportunity for these two foreign ministers to test each other's mettle on that.

GWEN IFILL: And there's no sense among the U.S. officials you talked to that the refusal to meet evenon the sidelines from Iran was a snub of any kind?

MARGARET WARNER: Well, you know, I don't -- they don't call it a snub.The way it happened was staffers at the lower level directly, not through intermediaries -- intermediaries talked about the possibility of the two men having some kind of informal encounter.

It was at the instigation of the U.S. The U.S. has made it very clear that it was at the instigation of the U.S.And one senior U.S. official just said to a group of us just now, you know, that was a little bit of a test. We want to make sure that the world knows that we're the ones always ready to talk.

But the clear indication they got was, as I said in my piece, that it was just too dicey for Rouhani back at home. And this official said, you know, it's one thing to meet with the French president, but it's another thing -- in Iran, the relationship with the U.S. remains just as -- he didn't say neuralgic.

He said it's controversial -- but as the U.S.-Iran relationship remains here ever since the '79 hostage crisis.And Rouhani has to tread very delicately. And a photo-op was definitely not in the cards for them.

GWEN IFILL: The president, as you know, has also had some tough words about the U.N. and its refusal to act, in his view, on Syria. Was there anything in his speech today, in his remarks addressed beforethe General Assembly which moved the ball on that?

MARGARET WARNER: You know, I wouldn't say it moved the ball.I think, Gwen, what he was -- what he wanted to indicate is, look, the threat of military action and U.S. military force is still out there.

We're willing to give the U.N. another shot at this to put its imprimatur with a strong resolution behind the deal that Lavrov and I negotiated. But there is -- and he didn't say it as a threat, but there's the implicit threat.

He didn't back down from the -- from his earlier proposal to use military force. So the ball is back in Russia's court, to some degree. Right now, I don't know if they have just finished, but Foreign Minister Lavrov and Secretary Kerry are having a meeting.

And, as we reported in the setup piece, they remain at loggerheads over whether the resolution should have embedded in it some sense that there will be consequences to be paid by Syria if it really doesn't comply.

GWEN IFILL: It's all really fascinating, Margaret.Thank you so much. And we will see you again from New York again.

MARGARET WARNER: See you again, Gwen.