JUDY WOODRUFF: For more on the humanitarian situation in Madaya and elsewhere in Syria, we turn to William Brangham.

WILLIAM BRANGHAM: As we just heard in Lindsey Hilsum's report, the United Nations is moving aid convoys into the besieged city of Madaya.

For the very latest on what's happening there and elsewhere in Syria, I'm joined via Skype by Kevin Kennedy, the U.N.'s regional humanitarian coordinator for the Syria crisis. He's monitoring the situation from Amman, Jordan.

So, Kevin Kennedy, thank you very much for being here.

We have seen all of these terrible images coming out of Syria. Can you give us the latest on what's happening in the town of Madaya?

KEVIN KENNEDY, United Nations: Well, as you know, we were able to deliver after many months of requests aid to Madaya last night for the 42,000 people that are trapped there, and also to two other towns to the north, Foua and Kefraya.

And we hope to provide some more deliveries in the next couple days here, because what we were able to do last night was — had some of the basic needs, but much more is required to meet their situation in Madaya.

WILLIAM BRANGHAM: I mean, we know that Assad's forces have surrounded these towns, sometimes with barbed wire, sometimes with snipers.

Have you seen any interference at all with the aid convoys that are going into these towns?

KEVIN KENNEDY: There was a delay last night, but I would not call it interference (INAUDIBLE) but basically unimpeded. It took a while to get there, but they did get there about 8:00 in the evening and stayed until 4:00 in the morning.

So, I would say this is just one town of many that are either besieged or hard to reach in Syria. There's about 13.5 million people in need of one form of humanitarian assistance or another in Syria. And about 4.5 million of those are in these hard-to-reach areas and half of those in ISIL-controlled areas.

WILLIAM BRANGHAM: Just as you say, Amnesty International referred to Madaya really as just the tip of the iceberg.

So, what are you doing in those other towns that have been harder to reach as well?

KEVIN KENNEDY: Well, we continue to try to reach them. And we do in some cases, but not near to the degree that we should.

The U.N., the Red Cross, Red Crescent, the NGOs are very active on the ground in Syria. In fact, it's quite remarkable, because of the degree of activity and assistance that's delivered in a very active war zone.

Some six million people are fed every month, every five non-food items, eight million people with clean water, but this is not meeting the needs that are there in Syria, particularly in those areas that are controlled either by ISIL or besieged by the armed groups or by the government.

WILLIAM BRANGHAM: The United Nations has passed resolutions demanding that the Syrian government allow these aid convoys in, but there has been very little success moving the needle there. What other levers do you have to try to get the aid into the places where it's needed?

KEVIN KENNEDY: Well, it's not just the Syrian government, though that's one part of the conflict. There's other group as well, ISIL and other armed groups that restrict our aid efforts.

We continue to work with the government to try to get access. And we have had some success, not the degree of success that we would like. We also deliver from outside the country, from Turkey, from Iraq, from Lebanon and from Jordan as well, into some of those hard-to-reach areas and negotiate with the different armed groups there to get through.

WILLIAM BRANGHAM: My understanding is that Monday's delivery and last night's delivery really will last for about four weeks. But what happens when that food runs out? What happens then?

KEVIN KENNEDY: We will be going back to the situation you had before, and the situation was quite dire.

It is interesting. A kilo of wheat was going for $89 in Madaya until yesterday. That same kilo goes for 75 cents in Damascus, which gives you an idea of the degree of deprivation that the people have suffered. And, of course, the concern is not only in Madaya, but these other locations, and what conditions are they in?

WILLIAM BRANGHAM: So there are some supplies in Madaya, but people just simply can't afford to purchase them?

KEVIN KENNEDY: Well, there is always a black market in any war, and there is a black market in this war.

And I guess some things leak into there, not in any great quantities, but obviously at great expense, and really beyond the reach of most of the people to buy them. If the price is 89 times what it should be, it gives you an idea of the degree of scarcity and the degree of how hard it is to get these supplies.

So, we have about 15 areas in Syria that we consider besieged, and another — and which contain about 400,000 people, and another four million people, if you will, in these hard-to-reach areas where we get in intermittently, but not with the consistency and the sustained effort that we need.

WILLIAM BRANGHAM: Some of the rebel groups have been arguing that until aid is allowed in freely into these towns, that the peace talks that are planned for the rest of — for the end of this month shouldn't go forward. Do you believe that that's the right strategy?

KEVIN KENNEDY: You know, we're calling for immediate, open, unimpeded and sustained access.

Of course, we have been calling on this for years. But this is a good moment to really put that into play. And I think all parties in conflict or all parties going to the peace conference should abide by this. Meeting the needs of the people, wherever they may be, in whatever area they're under the control of, is most important.

And denying people the basic necessities of life and putting their lives in danger is a violation of international humanitarian law and cannot be abided by.

WILLIAM BRANGHAM: All right, Kevin Kennedy of the United Nations, thank you very much for joining us.

KEVIN KENNEDY: Thank you.