JIM LEHRER: And to the crisis in Somalia, which is facing the worst famine in decades. The United Nations warned today 800,000 children could die from starvation. International agencies want to send in more food, but al-Qaida-linked militants vowed to block the aid.
Jonathan Rugman of Independent Television News traveled to a refugee camp just outside the capital, Mogadishu.
A warning: Some of the images in this report are very disturbing.
JONATHAN RUGMAN: Ahmed is eight months old and close to dying of hunger. He lies in the lap of his father, Abdi. The pair have traveled for four perilous days to Mogadishu from the famine zone of South Somalia in what Abdi knows is a desperate race against time.
These 1-year-old twins, Avshir and Nasir, have just arrived, just two of the half-a-million children the U.N. says are seriously malnourished. The boys' mother says she walked to the capital because there's nothing to live on outside. And she's smiling because she is lucky to have made it this far.
Over 1,000 infants have been brought to this emergency nutrition center since it opened just a few days ago. Their mothers are so busy trying to save their children's lives, that there's barely time to grieve for the dead children they have left behind.
This feeding center is just a few hundred meters from the front line of Somalia's never-ending civil war. And these refugees have risked everything to come here, to cross that front line, to escape from the famine zone in the countryside, where tens of thousands of people have already died.
This is how our journey begins, in the only safe mode of transport U.N. aid workers have, in the backs of armored vehicles manned by peacekeepers from Burundi wielding machine guns -- through the window, glimpses of the failed capital of a failed state. On the road out of Mogadishu, we can see some of the 400,000 refugees living in makeshift camps.
First, they fled the fighting. Now it's famine and drought.
ROZANNE CHORLTON, UNICEF: If you have one of those and you want to travel, what do you do?
JONATHAN RUGMAN: We reach the Badbaado camp, where UNICEF's director for Somalia is dressed as if for battle. She can't know how many in this teeming tent city are sympathizers with militants linked to al-Qaida. And everywhere, there are men with guns, militiamen from squabbling rival clans, as well as Burundian forces keeping watch in case food queues turn into riots.
How old are you?
On this pickup truck, there's what looks like a child soldier. He says he's 18. His cousin says he's 13, the latest recruit to Somalia's decades-old cycle of violence. And if delivering aid amid Mogadishu's ruins is difficult, imagine how hard it may prove where famine has been declared.
ROZANNE CHORLTON: We're hopeful that we can push further into southern Somalia in the coming days and weeks. We have to try. We can't not try. It's just too serious.
JONATHAN RUGMAN: And here's the proof: little boys like Saad, age 7, listless in his mothers arms. She says the Islamists tried to stop them from reaching the capital, the fighters apparently in denial about what the U.N. calls the worst humanitarian disaster in the world.
Tens of thousands are seeking sanctuary in this camp, yet what we have filmed cannot capture the scale of this crisis, with millions of Somalis beyond the reach of anyone's help.