President Obama declared Tuesday that the Ebola epidemic in West Africa could threaten security around the world, and he ordered 3,000 U.S. military personnel to the region in emergency aid muscle for a crisis spiraling out of control. An ominous World Health Organization forecast said that with so many people now spreading the virus, the number of Ebola cases could start doubling every three weeks. "If the outbreak is not stopped now, we could be looking at hundreds of thousands of people affected, with profound economic, political and security implications for all of us," Obama said Tuesday after briefings in Atlanta with doctors and officials from the Centers for Disease Control and Prevention and Emory University.