GENEVA - Nearly 1.4 million children are at "imminent risk" of death in famines in Nigeria, Somalia, South Sudan and Yemen, the UN children's agency UNICEF said on Tuesday.People are already starving to death in all four countries, and the World Food Program says more than 20 million lives are at risk in the next six months."Time is running out for more than a million children," UNICEF Executive Director Anthony Lake said in statement."We can still save many lives. The severe malnutrition and looming famine are largely man-made. Our common humanity demands faster action. We must not repeat the tragedy of the 2011 famine in the Horn of Africa."