GWEN IFILL: A small American team of military, law enforcement and hostage negotiators is arriving in Nigeria today to help the girls.

For more on that effort, I'm joined by U.S. Assistant Secretary of State for African Affairs Linda Thomas-Greenfield.

Thank you for joining us.

LINDA THOMAS-GREENFIELD, Assistant Secretary of State for African Affairs: And thank you for having me.

GWEN IFILL: Give me your best assessment as of this evening of where the girls are.

LINDA THOMAS-GREENFIELD: Gwen, I wish I could tell you where the girls are. I don't think we have an answer to that. And I know the Nigerians don't have an answer to that.

They have been missing for more than 24 days. An I think the question that everyone has is where, where are the girls?

GWEN IFILL: There has been some speculation that they have been split up in different locations?

LINDA THOMAS-GREENFIELD: We have heard that speculation, that some may have been taken across the border into neighboring countries or maybe in different locations inside of Nigeria in the forest, and also in some small villages.

But, again, this is all based on rumor and information that we have not been able to confirm.

GWEN IFILL: Everybody, from your boss, Secretary of State Kerry, this morning, to the president of the United States, has said the U.S. will do all it can do. What can the U.S. do?

LINDA THOMAS-GREENFIELD: We will do all we can do.

And the president has instructed us to do that. We are starting by sending a multidimensional team in that will include the military, civilians, individuals that can work with the Nigerians on how to negotiate and how they can approach returning the girls without harming them.

GWEN IFILL: I know you are a diplomat, rather than a military person, but does this mean we're not going have any kind of military intervention in this situation?

LINDA THOMAS-GREENFIELD: At this time, there are no plans that this is a military intervention. We are sending military advisers in to work besides the Nigerians and provide advice and support to the Nigerians in their efforts to retrieve these girls.

GWEN IFILL: What about satellite and drone imagery? That might help.

LINDA THOMAS-GREENFIELD: The Nigerians have asked. And this is something that we are considering — not drones, but satellite imagery.

There is commercial satellite imagery that could be available to assist in this effort and it is something that is being considered.

GWEN IFILL: You just mentioned that the Nigerians have asked for that help. There seemed to be some delay in the U.S. offer of help in this situation and Nigeria's willingness to accept it. What was that gap about?

LINDA THOMAS-GREENFIELD: We have not delayed an offering of the Nigerian assistance.

We started working with the Nigerian government on providing assistance several months ago. We have had conversations with military elements, as well as the national security adviser. I was out in Nigeria in December with General Rodriguez and other team members from USAID. We had some very productive discussions with the Nigerians on how we might be able to assist.

Some of that assistance has already been provided to the Nigerians in terms of helping them coordinate their own intelligence information, giving them advice based on our own experience in having dealt with counterinsurgencies in Iraq and Afghanistan.

GWEN IFILL: So you are speaking specifically about cooperation on the part of the U.S. and the Nigerian government to Boko Haram?

LINDA THOMAS-GREENFIELD: Yes.

GWEN IFILL: Is that — Boko Haram has been a problem for some time, so what progress has been made in that joint effort?

LINDA THOMAS-GREENFIELD: As you know, back in November, the U.S. government made a decision to sanction Boko Haram. And so they are on our terrorist list.

And that gives us the ability to look at what kind of financing there they have and also to look at flows of money that they maybe have — may have going in their direction. But this is a difficult task, as they are basically a group of bandits that are hiding among populations. And it's made it very difficult for the Nigerians to capture them.

GWEN IFILL: I think it's fair to say the U.S. and other nations knew all that about Boko Haram before November. So why did the designation not happen until then?

LINDA THOMAS-GREENFIELD: I think we started working on it long before November. It's a long process to make a designation.

And the efforts that went into getting that designation done finally was completed in November.

GWEN IFILL: You have to explain to people who don't know what you are talking about like me what is the long process. What takes so long when the actions are so obvious.

LINDA THOMAS-GREENFIELD: Yes.

We have to — one thing, we have to make sure that we have it right. The people we are making the decision put on the list, it has to go through a process with the Department of Treasury, with the Department of Justice. And all of the work that needed to go into that process was done and led us to come to the decision to make the designation in November.

GWEN IFILL: We are now aware of al-Qaida affiliate cells, however you want to describe them, at work not only in Nigeria, but also in Sudan and Somalia.

Is there a coordinated regional effort to try to break that up?

LINDA THOMAS-GREENFIELD: I think, regionally, we have had a number of discussions with the African Union and with the regional players across the continent to address the scourge of terrorism that is taking place in a number of locations, whether it's in Somalia and Kenya with Al-Shabab, with the counter-LRA effort, and also with Boko Haram and AQIM and al-Qaida.

I think that it has to be a multiregional effort, and we're certainly working with our partners across Africa to address this issue.

GWEN IFILL: Do you feel that you're making progress?

LINDA THOMAS-GREENFIELD: I think we're making slow progress, but there's still a lot of work to be done.

GWEN IFILL: Linda Thomas-Greenfield, assistant secretary of state for African affairs, thank you so much for helping us out.

LINDA THOMAS-GREENFIELD: And thank you very much for having me.