ARI SHAPIRO, HOST:

Iran has launched missile attacks on U.S. troops in Iraq. Iran's government says this is retaliation for an American drone strike that killed a top Iranian commander last week. Iran's Revolutionary Guard Corps calls the attack hard revenge and warns that it will respond to any U.S. counterattack. The Pentagon has confirmed strikes by more than a dozen missiles on bases where there are U.S. troops. It says it is assessing the damage. Here is sound of a video apparently taken by Iraqi troops around one of the bases that was hit.

(SOUNDBITE OF ARCHIVED RECORDING)

UNIDENTIFIED PERSON: (Shouting in non-English language).

(SOUNDBITE OF EXPLOSION)

UNIDENTIFIED GROUP: (Shouting in non-English language).

(SOUNDBITE OF EXPLOSION)

UNIDENTIFIED PERSON: (Shouting in non-English language).

SHAPIRO: Sound there of the attack early this morning Iraq time. This is a breaking news story. Details are coming in fast, and there are conflicting reports. There's also a lot that we still don't know. NPR's Jane Arraf is in Baghdad, where, I believe, it's just after 5:30 a.m. Jane, is that right?

JANE ARRAF, BYLINE: It is.

SHAPIRO: All right. Tell us what we are hearing in that video.

ARRAF: So in that video, they're saying, be careful, be careful. And then you hear that explosion, and then they're calling out to one of the officers. And they're telling each other to take cover. But before that in that video, which is being widely played, they're saying, they're targeting the Americans, because al-Asad, the base where this has hit, is a huge base, the size of a small city. It houses about 1,500 U.S. and other coalition forces, but it also has a big Iraqi presence there. And Iraqis have also suffered in these attacks. This is a base where they've been doing anti-ISIS operations near the Syrian border and in the western desert.

But it wasn't the only attack, Ari. There were also targets in Irbil, in the Kurdistan region of Iraq. One of them landed near the military side used by the U.S. of the Irbil airport but apparently did not explode and caused no casualties. No word of other casualties yet. One of the other strikes in the Kurdistan region was said to have been on a Kurdish-Iranian opposition camp.

SHAPIRO: Now, I know that there is some news as well out of Iran about the timing of these attacks relative to the burial of Qassem Soleimani. What can you tell us about that?

ARRAF: Well, really dramatic scenes of Soleimani being buried. They actually delayed the burial, it seems, partly, because of a stampede earlier because there were so many people - and dozens killed in that stampede - but also because this retaliation, they have said, was in memory of Soleimani, the top Iranian security commander who was killed by the drone strike - the U.S. drone strike in Baghdad on Friday. They actually dubbed it Operation Martyr Soleimani (ph). And Iran is vowing retaliation. One of the Revolutionary Guard commanders says this is the first step, and Tehran will not spare Americans.

SHAPIRO: We don't know yet whether there were American casualties in these attacks, but we do know that the U.S. was bracing for some kind of retaliation from Iran. And yesterday, you reported that helicopters were ferrying U.S. and coalition troops from place to place. This was after the Iraqi parliament voted to expel U.S. forces from Iraq. What can you tell us about the location of Americans in the country and whether they were moved out of harm's way?

ARRAF: Well, those flights have continued tonight out of the Green Zone, with helicopters flying people out. The Pentagon had said that U.S. forces are not leaving, but they had said that before these attacks on Iraqi bases, where U.S. forces are housed. They have been moving out coalition members from other countries, which have announced that they have suspended their operations, and they're moving their people to safer places. You know, the U.S. forces that had moved out of bases - some of them had moved out of bases that were more in harm's way, such as the one in the Green Zone, were, in some cases, moved to other bases in Iraq. But now it's clear those bases aren't safe either, so we are waiting to hear whether there will be movements of U.S. troops outside the country.

SHAPIRO: That as NPR's Jane Arraf in Baghdad on this unfolding news story of Iranian attacks on bases that housed U.S. forces in western Iraq and northern Iraq.

Jane, thank you very much.

ARRAF: Thank you. Transcript provided by NPR, Copyright NPR.