GWEN IFILL: Now we turn back to Prime Minister Netanyahu's speech to Congress, the threat of Iran, and what, if anything, makes for a good nuclear deal.

I'm joined by two foreign policy veterans. Stephen Hadley was national security adviser for President George W. Bush. He's now the chairman of the board of directors at the U.S. Institute for Peace. And Vali Nasr is a former State Department official and current dean of the Johns Hopkins School of Advanced International Studies.

Vali Nasr, let's start with you.

What was your first reaction to the speech?

VALI NASR, Johns Hopkins School of Advanced International Studies: Well, I think the content of the speech wasn't new. We knew where the prime minister of Israel stood on the deal.

But I think one can say that the way that he laid out the case, it will make it much for difficult for the United States government and Iran to arrive at a deal, because I think the field has been significantly narrowed for the president in particular in order to argue a deal with Iran is actually a good deal. I think the definition of a good deal was largely defined by the prime minister of Israel today.

GWEN IFILL: Steve Hadley?

STEPHEN HADLEY, United States Institute of Peace: I think it was a very effective presentation. People said that the arguments were not particularly new, but a lot of Americans had not heard them in such detail.

I think it was a forceful presentation. I think it will have the impact that Vali said. I think in some sense it makes it probably harder for both Iran and the administration to make concessions. And I think probably Prime Minister Netanyahu helped himself a little bit in this upcoming Israeli election.

GWEN IFILL: So if we think that this speech today could have put a spanner in the works of these negotiations that are under way in Switzerland right now, the president's criticism of them today was that there was no alternative presented. Is there an alternative to this negotiation?

VALI NASR: There's no alternative to the negotiation.

I think what the prime minister of Israel was saying was generally that he doesn't agree with any concessions or compromises. You can't have negotiations with those. I think what he argued, that instead of negotiating with Iran on the terms of the deal, you have to lean on them heavily through sanctions and perhaps even a military option until Iran eventually surrenders the program.

And that's not likely to happen, because I don't think the military option in today's Middle East is viable. It's not a given that we can go back to sanctions. And I think the president's case is that you have to give diplomacy a chance. The president of Israel was saying there is no diplomatic path with Iran.

And I think you have to — people will have to come down as to whether they believe the president that there is a diplomatic path, it's possible to have a deal, or they believe the prime minister of Israel that says there's no diplomacy with a country that you can't trust and that ultimately it's going to find its way to a bomb through diplomacy.

GWEN IFILL: But I heard the prime minister say two things, that there should be a better deal, which implies that there should be more diplomacy, and also that there isn't a military option. Did you hear that?

STEPHEN HADLEY: I heard the better deal.

I think he believes that greater sanctions and more time could result in greater concessions by the Iranians. It's difficult. I think the dilemma for the administration, they will still try to see if they can get a deal. I think they know today the kind of deal that will work in terms of the region, in terms of our ally Israel and in terms of a Congress.

And the real question is, if they cannot get that deal, whether they will decide to it's better to say, we can't get there at this time and talk about further extension, and the question is whether the Iranians would accept an extension of the joint program of action, which does constrain their program, to allow more time for negotiation.

Then the flip side is, more time with negotiation, can you actually get a better deal?

GWEN IFILL: Now, it seems very confusing, right? What we know of what's on the table is a 10-year freeze in nuclear enrichment and then a year to allow it to be enforced. Is that something which — that's the kind of — those are the outlines of a deal that I think the prime minister said would pave the way to a bomb.

VALI NASR: Ultimately, this is — the problem as far as Israel sees it is that, A, this is not a permanent deal, and, B, that it's — Iran retains the right to enrichment.

But I don't think actually the problem is so much a technical agreement between Iran and the U.S. It's that both sides have to be able to sell this deal back at home. And from the Iranian side now, they see that the administration can come to a negotiation table and negotiate, and then you have this force outside in the form of the prime minister of Israel which at any point in time can come and put pressure on the administration and narrow its ability to sell the deal at home.

That makes it very difficult for them to negotiate. And I think the Iranians can come up with any set of excuses as to why they can't agree to this freeze. But I think, right now, they're really worried that the administration is unable to deliver a deal because of the Congress.

GWEN IFILL: Do you agree with Steve Hadley that Netanyahu helped himself politically at home?

VALI NASR: Well, I think the reception he got in Congress definitely helped him.

I think we have to see whether the Israeli public will see any further fallout from his visit here. But, barring that, I think they would see that he was able to come here, was received well by Congress, and made his case, and no damage is done so far.

GWEN IFILL: Elaborate what you meant by that.

STEPHEN HADLEY: Well, I still think that there is an opportunity for a deal here. I think it is still the case that in some sense the alternatives for both parties for not reaching a deal are not attractive.

I think it will be a challenge for the United States to keep sanctions in place, and, of course, without a deal, Iran doesn't get potentially relaxation of sanctions. So I think there's still a reasonable chance that we will get an agreement.

The question is, can the Congress — will the president of the United States be able to sell it to the Congress?

GWEN IFILL: There's a March 24 deadline for this — for these negotiations which are currently under way in Switzerland. What are the chances they can be achieved?

VALI NASR: I think the chances are narrow. I think there is a chance that they agree to some kind of a formula…

GWEN IFILL: By this date.

VALI NASR: By this date, that they agree to some kind of a formula that would extend the negotiations, would give gains to both sides.

But, again, the dilemma is that the way it's happening now is that, to the Iranians, it doesn't look like President Obama is the only decision-maker here.

GWEN IFILL: And it seems like Zarif and Kerry are kind of in a box.

STEPHEN HADLEY: They're in a box.

They will — but let's be fair. We have heard the case against this deal, this hypothetical deal. The president says they haven't reached a deal. I think we should all keep our powder dry, see if there is a deal, let the president of the United States and the secretary of state make their case, and then the American people will have to decide.

And the question will be — this is not going to be the deal that many people had hoped for. It doesn't roll back the program as far as people would have hoped. It's probably not as long a duration. The question the American people will have to decide is, if this is a deal, you know, what do you do then. And that I think is a subject on which there ought to be some vigorous debate.

GWEN IFILL: Stephen Hadley of the U.S. Institute of Peace and Vali Nasr at the Johns Hopkins School of Advanced International Studies, thank you both very much.

VALI NASR: Thank you.