GEOFF BENNETT: U.S.

forces formally withdrew from Iraq today, marking the end of a long and turbulent military presence.

The withdrawal brought celebrations in the capital, but also concern about what comes next.

Thousands gathered on the streets of Baghdad for a celebration more than 20 years in the making, the military trucks and soldiers in fatigues, this time Iraq's very own, as the U.S.

announced its forces have officially left the country.

Iraq's prime minister called the withdrawal an opportunity.

ALI FALEH AL-ZAIDI, Iraqi Prime Minister (through translator): A new phase has begun, one defined by Iraq's sovereignty, the strength of its institutions, the readiness of its forces, and balanced partnerships with its friends.

GEOFF BENNETT: But as the war in Iran expands and draws in neighboring countries, U.S.

bases in the northern Kurdish region have come under attack.

And the Kurds who remain fear further attacks by Iran-backed groups or the resurgence of the Islamic State.

OSMAN KAMUSASHI, Erbil, Iraq, Resident (through translator): I don't favor this at all.

I mean, the departure of the American army and the coalition from the Kurdistan region will impose a serious threat on the Kurdistan region.

And there is another threat, which is the restructure and the return of the Islamic State.

GEOFF BENNETT: Despite those concerns, the U.S.

was facing a deadline.

The withdrawal had been agreed to two years earlier under former President Biden and was ultimately carried out by President Trump.

The Pentagon called the orderly departure a milestone that reflects the success of a 12-year campaign that defeated ISIS and said it will continue to provide targeted training and intelligence support.

That continued support is still a dramatic scale-down from more than two decades of U.S.

military involvement in Iraq.

U.S.

forces invaded in 2003 and toppled the country's oppressive dictator, Saddam Hussein.

The first U.S.

withdrawal came in 2011, only for U.S.

troops to return three years later to help Iraqi forces fight ISIS.

Decades of brutal fighting resulted in the deaths of more than 4,000 U.S.

troops and hundreds of thousands of Iraqi civilians.

Now, as Iraqi leaders tout strength and sovereignty, the world watches to see if Iraq can withstand outside forces.

For insight and analysis of the formal U.S.

withdrawal from Iraq, we turn now to James Jeffrey, who served as ambassador to Iraq under former President Barack Obama and was the special envoy to the Global Coalition to Defeat ISIS in the first Trump administration.

And Feisal Istrabadi served as Iraq's ambassador to the U.N.

after the U.S.

deposed Saddam Hussein.

He's now a professor at Indiana University.

Welcome to you both.

And, Jim, we will start with you.

What does the U.S.

withdrawal from Iraq change practically starting today?

JAMES JEFFREY, Former U.S.

Ambassador to Iraq: Practically, what it changes is a mission accomplished.

In a time where we have not had that many successful military operations, this one from 2014 on was spectacularly successful in defeating a major terrorist entity, the Islamic State.

We did it, tragically, with casualties, but very, very few compared to our other wars.

And we did it with the cooperation of Iraqi and Syrian officials.

That's very important.

But the bottom line was, when it was finished, they said, we would like you to go at this time, and we said, fine.

It doesn't change very much, because, as we just heard, we will still have a military presence, as we did after 2011, when I was ambassador, under the embassy.

It's a technical formality, but it is an important one, because they're not under military command.

They're not fighters, but they're trainers, equippers.

They provide intelligence support, and they can call in real American military power if they need to.

So we will still have that in place if Iraq needs it.

GEOFF BENNETT: Feisal Istrabadi, we know, of course, that the U.S.

left Iraq before in 2011, returned three years later to fight ISIS.

What's different this time?

FEISAL AMIN AL-ISTRABADI, Former Deputy Iraqi Ambassador to United Nations: On the surface, what's different is that, when the United States returned in 2014, something like a third of the country was occupied by a terrorist organization which sought to erase an internationally recognized border between Iraq and Syria.

We don't have that.

What we -- what is the same is a deep skepticism as to whether or not Iraqi forces will be able to secure the country at a time when Iraq, A, has both -- has both been a target of the ongoing Israeli-American and Iranian war, as well as having its territory used to launch attacks against its neighbors with which Iraq is not at war.

That remains to be seen.

In 2011, when the United States withdrew, I must disagree somewhat with my colleague, a lot of intelligence cooperation ceased between Iraq and the United States.

And the end result of that was the rise of ISIL.

I remain deeply concerned that that may be what is in Iraq's future.

So I'm skeptical about this withdrawal.

I would also add that this is, I think, a strategic defeat for the United States, in this sense that it was also supposed to be -- today was supposed to be the date on which the pro-Iranian militias in Iraq were disarmed, and that is not taking place.

GEOFF BENNETT: Well, on that point, Iran-backed militias were supposed to be brought under greater control of the Iraqi government.

That hasn't happened.

How significant is that?

And how involved is Iran in Iraq?

JAMES JEFFREY: It's all very significant.

And, there, I agree with my colleague.

In terms of the Islamic State, they're defeated.

Nothing is left but a few cells.

There are more in Syria, but we have that situation under control because we still have our overall operation focused on that out of Jordan.

But the problem is that Iran has slowly, through political parties and through these militias, tried to build up a presence like they have in Lebanon in Iraq.

That's something the handful of U.S.

forces could not stop.

In fact, they were there from 2014 to today, and they didn't stop it.

I agree that the pro-Iranian side is pitching this as a victory.

We drove out the oppressor, but very few people in Iraq really believe that.

But I agree also Iraqis are nervous because, if anything - - nothing else, American military presence is a symbol that we will be back.

We showed last time when we left that, in extremis, we would come back, but everybody wonders, will they come back?

Whereas, if you have got boots on the ground, it's pretty certain that you will stay and reinforce them, rather than retreat.

GEOFF BENNETT: And what does all of this mean specifically for the Kurds?

The prime minister of the Kurdistan regional government has made his unhappiness widely known about this formal withdrawal.

FEISAL AMIN AL-ISTRABADI: Yes, I understand that, and I sympathize.

However, I think it was always an overreach for the Kurds to rely too much on the United States to resolve the problems between Erbil, the capital of the Kurdistan region of Iraq, and Baghdad, the capital of Iraq.

I think that there needs to be an inward-looking dialogue within the Iraqi political class in which the American Embassy needs to be a convener at times, an encourager.

But to rely on the United States as sort of the intervener in on behalf of the Kurds with respect to Baghdad, or vice versa, was always a mistake.

And this may actually, if one wants to be optimistic, encourage a better political process domestically.

GEOFF BENNETT: As we wrap up this conversation, we can't lose sight of the fact that more than 4,000 American service members were killed in Iraq, along with more than 200,000 Iraqi civilians, as you both well know.

That's roughly the entire population of a city like Richmond, Virginia, or Des Moines, Iowa.

As this chapter closes, how do you begin to assess what was achieved against the human cost of that magnitude?

JAMES JEFFREY: First, Saddam Hussein, who had terrorized the region from 1980, his accession to power, until he was deposed in 2003, was removed, most Iraqis I have talked to, and that is in the thousands now, do not regret us getting rid of him.

Furthermore, Iraq is still, for all of its flaws, one of the few democracies in the Middle East, and the country still has political parties and political factions arguing in Parliament and in the courts, rather than on the battlefields.

So those are two big pluses.

We don't want to see Iraq go the way that Syria went between 2011 and just two years ago, a total civil war.

That was a possibility if we had not intervened.

So I would say it's mixed, unlike Afghanistan.

That's a failure.

Iraq, call that mixed.

GEOFF BENNETT: Mixed.

How do you see it?

FEISAL AMIN AL-ISTRABADI: As Zhou Enlai supposedly said about the French revolution, too soon to know.

But I think that I agree generally with the assessment.

Look, what I think the Americans gave the Iraqis in 2003, paid for with the lives of a lot of Iraqis and Americans as well, is hope that the future need not be what it had been under Saddam Hussein.

Saddam Hussein is responsible for the deaths of one million Iraqis in ruling Iraq from 1979 until 2003.

There is hope that that is -- that the future will be better than the past.

That would not have been possible without the American intervention in Iraq.

Have things gone swimmingly since 2003?

No, there were many, many mistakes made by the Americans, many mistakes made by the Iraqis.

But, fundamentally, there is hope that the future will be better than the past.

GEOFF BENNETT: Ambassadors Feisal Istrabadi and Jim Jeffrey, my thanks to you both.

JAMES JEFFREY: Thank you.

FEISAL AMIN AL-ISTRABADI: Thank you very much.