Gangs of thin young men armed with AK-47 assault rifles race down drought-parched roads in Land-Rovers mounted with machine guns.

Emaciated women and children languish in the burning desert sun, starving, while truckloads of rice and flour pass them by. Disease and death stalk wretched refugee camps.

That was 1981 in Somalia. Today, the same scenes are replayed for U.S. troops in their unprecedented race against time to deliver food to starving Somalia.

Why is so much of the Horn of Africa such a perpetual setting for human suffering? Why so many humanitarian missions over so many years?

Decades of warfare, prolonged drought and overpopulation are the chief culprits, say experts about the chaotic region that includes all of Somalia, Ethiopia and Djibouti, southern Sudan and northern Kenya.

Wars--clan, ethnic, religious, civil and international--also have created what has been called the world's worst refugee problem. The United Nations estimates that Ethiopia and Somalia together shelter more than 1.3 million refugees. More than 70% are ethnic Somalis.

"It's really a combination of things. One is the environment," geographer H.J. de Blij of the University of Miami said. "You're dealing with an area with a very, very sensitive ecological balance. The slightest disturbance of that balance is going to create loss and human misery."

Although statistics from war-plagued eastern Africa are not available, reports indicate that major portions of the continent are in the midst of a cycle of below-normal rainfall that has lasted nearly 25 years.

"It's probably the worst drought of this century down in Zimbabwe, Zambia, Botswana, Mozambique and parts of northeastern South Africa," meteorologist David Miskus of the National Oceanic and Atmospheric Administration said.

Called the jiilaal in Somalia, the drought is terrifying, and warfare magnifies its effects.

During the short rainy season, people in dry areas collect water in reservoirs dug out of the ground. But these are susceptible to sabotage by rival groups, such as Somalia's fierce clan families.

Before the last Somali government fell in 1991, troops under President Mohamed Siad Barre destroyed water holes in rebellious areas.

Ethiopia's 30-year civil war, which in May, 1991, resulted in future independence for the breakaway province of Eritrea, exacerbated the effects of famine and made relief efforts difficult.