The organization's humanitarian coordinator says more than 20 million people are threatened by famine and starvation.They're concentrated at four countries,the African nations of Nigeria,Somalia and South Sudan,and the Middle Eastern nation of Yemen.The U.N. says this constitutes the worlds greatest humanitarian crisis since 1945,when the U.N. was founded.

    What are those countries have in common?Conflict.

    In Nigeria,it's the fighting against the Boko Haram terrorist group,combined with potential famine that has devastated parts of the country.

    In South Sudan,fighting between government troops and armed groups,combined with a famine,have left more than 40 percent of the population in need of food,farming help and nutrition.

    In Somalia,attacks by the Islamic militant group al Shabaab,plus a worsening drought are taking their toll and in Yemen,a two year old civil war has left roads blocked,reduced imports,left markets damaged and left millions hungry.

    So,what can be done about this?

    The United Nations wants funding,$4.4 billion by this summer that would go toward fighting hunger and disease in these countries.