WILLIAM BRANGHAM: Welcome to the "NewsHour."

There is an uneasy calm tonight across the Middle East after both Israeli and Iranian officials had muted responses to Israel's apparent retaliatory strike in Central Iran.

The region had been on edge since an unprecedented Iranian attack on Israel and Israeli vows of revenge.

Nick Schifrin has more -- Nick.

NICK SCHIFRIN: William, it is not every day that something explodes near an Iranian military base during a time of intense regional tension.

But, today, that is exactly what happened, and all sides are trying to downplay it.

Near the central city of Isfahan this morning, Iran's air defense targeted what Iran called small drones.

But former military and intelligence officials tell "PBS NewsHour" this was an Israeli strike near an Islamic Revolutionary Guard base and Iran's nuclear technology center.

By day, Iranian state TV showed Isfahan quiet.

WOMAN: Life is going on according to normal.

NICK SCHIFRIN: And a local Iranian military commander said there's nothing much to see here.

BRIG.

GEN. SIAVASH MIHANDOOST, Iranian Senior Commander (through translator): The sound heard early in the morning today in Isfahan was not an explosion.

It was our powerful air defense firing at a suspicious object.

It caused no damage or incident at all.

NICK SCHIFRIN: Which apparently is how both Iran and Israel wanted it.

Iranian officials did not blame Israel.

Israeli officials refused to claim credit.

The only exception was an indirect criticism.

Far right national Security Minister Itamar Ben-Gvir tweeted one word that best translates to "lame."

But, in Italy, after meeting Secretary of State Antony Blinken, Italian Foreign Minister Antonio Tajani revealed this: ANTONIO TAJANI, Iranian Foreign Minister (through translator): The U.S. was informed at the last minute, but there was no sharing by the U.S.

It was mere information.

But I think that what happened was also the result of the work of the G7.

NICK SCHIFRIN: For six days, President Biden and the Group of 7 industrialized countries urged Israel to show restraint to Iran's unprecedented April 14 attack, with more than 300 missiles and drones, launched from Iran toward Israel.

That was a response to Israel's killing seven senior Iranian generals in an Iranian consulate building in Syria.

In public, all U.S. officials would say today, the U.S. didn't play any part.

ANTONY BLINKEN, U.S. Secretary of State: I'm not going to speak to that, except to say that the United States has not been involved in any offensive operations.

NICK SCHIFRIN: And European leaders today urged more restraint.

URSULA VON DER LEYEN, President, European Commission: It is absolutely necessary that the region stays stable and that all sides refrain from further action.

NICK SCHIFRIN: At one point last night, the U.S. was so concerned about further violence, it restricted the movement of U.S. officials inside of Israel.

For perspective, we now turn to Suzanne Maloney, vice president and director of foreign policy at the Brookings Institution, a Washington, D.C., think tank whose work focuses on Iran and the Middle East.

Suzanne Maloney, thanks very much.

Welcome back to the "NewsHour."

What do you think the message is that Israel is sending to Iran with this strike?

SUZANNE MALONEY, Saban Center for Middle East Policy, Brookings Institution: Thanks so much, Nick.

I'm glad to be here.

I think the Israelis were trying to demonstrate to Iran that they can penetrate Iran's air defense system.

Obviously, the Iranians weren't able to do the same in their strike on Israel.

And they're also, I think, trying to demonstrate the capabilities that the Israeli military can bring to bear.

It did so in a very calibrated and, I think, focused way in this attack last night.

But the message from the level of sophistication of this operation, from what we're learning from the press and some of the reporting that's being done, suggests that this is something that would pose a real threat to Iran if, in fact, Israel chose to attack Iran's nuclear sites or other key elements of its military industrial complex.

NICK SCHIFRIN: Why pose a threat to Iran?

I pointed out that this location is near a major IRGC base, Islamic Revolutionary Guard Corps base, and some nuclear facilities.

So why does that particular message land well in Iran?

SUZANNE MALONEY: Well, because I think, for a very long time the Iranians have been quite concerned about a potential Israeli strike on their nuclear infrastructure.

They have taken a lot of steps, including the air defense system, to try to ensure that the Israelis could not succeed in doing so.

I believe that the strike last night demonstrated that the Israelis in fact could, if they chose, take out key nodes of the Iranian nuclear program.

Obviously, to destroy the program as a whole would take quite a bit more capacity and probably necessitate the involvement of the United States.

But, still, this strike sent a message to Iran, and I think the message was received.

NICK SCHIFRIN: And yet, at the same time, we saw a little bit of criticism implicit from the Israeli far right that this didn't go far enough.

This was not a direct mirroring of the attack by Iran on Israel, of course, more than 300 drones and missiles fired from Iran toward Israel.

This is not the same scale, nor did Israel claim credit for this attack.

Why?

SUZANNE MALONEY: Well, I think the Israelis are reacting in a way that's responsible and calibrated.

And that is actually important to ensuring that they don't find themselves spiraling up in an escalatory way out of control.

I think the United States and the G7 leaders, as you suggested in your report, have also been influential on helping to persuade the Israelis that they have time and space to demonstrate to the Iranians that there will be a price to be paid for the attacks that took place last weekend.

The Iranian attack, as you note, was completely disproportionate to anything we have ever seen.

It was absolutely unprecedented.

And I suspect what we saw last night was just the first of a number of steps that the Israelis will take to make sure that Iran does not repeat that kind of attack again.

NICK SCHIFRIN: Why is Iran downplaying this attack, practically suggesting that it never even happened?

SUZANNE MALONEY: That's actually par for the course for the Islamic Republic.

There have been a number of other incidents over the years, whether it's assassinations of nuclear scientists that have been attributed to Israel, the spiriting away of the Iranian nuclear archives that was also done by Mossad.

The Iranians have never, in fact, acknowledged that these incidents took place.

They usually try to blame them on other terrorists or other types of incidents.

They want to reassure their own population that they're fully in control.

And I think that there is a desire to avoid any sense that there is the potential of a larger military conflict.

NICK SCHIFRIN: We saw yesterday a mid-level Iranian commander suggesting that any further violence could change Iran's nuclear posture.

Of course, Iran claims that its nuclear program is entirely civilian.

What impact do you think this latest violence could have on the thinking of Iran's leadership about possibly pursuing nuclear weapons?

SUZANNE MALONEY: Well, I think it's quite clear that the long commitment and the amount that the Iranians have invested and what they have paid in terms of their international isolation and sanctions suggests that this isn't simply a civil nuclear objective that they have with respect to their nuclear program.

Everything that we know from the archives and other sources suggests that it's very clearly designed for military purposes.

They have not yet, of course, taken the final steps.

They haven't weaponized.

There are other things that the Iranians could do that could move them even closer than they are today, which is closer than any point in history, to nuclear weapons capability, such as leaving the Non-Proliferation Treaty or fully kicking out the International Atomic Energy Agency.

And I think there's a lot of trepidation in the international community about those kinds of moves.

It would be a very serious step by the Iranian government.

And I think nobody wants to precipitate that kind of an outcome.

NICK SCHIFRIN: And, finally, you have pointed out that the current generation of Iranian leaders is different than the previous generation of leaders that came to power in 1979, when the shah was overthrown.

And that new generation, you have said, is more dangerous and unpredictable.

Why?

How important is that?

SUZANNE MALONEY: I think what we have seen over the course of the past decade or so is an increasingly risk-tolerant Iranian leadership.

Those who've served on the front lines and who've been deeply involved with Iran's development of a proxy network across the broader Middle East who want to use force, prepared to use it.

They have engaged in the kind of behavior we have seen that's targeted former senior U.S. government officials, so that such that some of them are still under protective custody.

They have also, of course, jumped on board with the Russian war in Ukraine in a way that no other country in the world has by supplying drones that have made a major difference in Russia's effort there.

So, I think what you see is a leadership that is more prepared to engage in malign behavior and feels insulated by its relationships with Russia and China.

NICK SCHIFRIN: Suzanne Maloney of Brookings, thank you very much.

SUZANNE MALONEY: Thank you.