One week after ramping up the American effort to help combat the Ebola outbreak, President Obama went to the United Nations to warn that other nations are lagging behind.

"Right now everybody has the best intentions, but people are not putting in the resources that are necessary," Obama said. "It's a marathon, but you have to run it like a sprint."

"Do not stand by thinking somehow because of what we've done it's taken care of. It's not," he said.

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Obama gave an update on the U.S. response he unveiled last week at the Centers for Disease Control and Prevention, announcing that the new military commander center in Liberia is "up and running."

He said Gen. Darryl Williams, who is heading the U.S. military effort, is "on the ground in Monrovia" and that military teams are working as quickly as they can to bring in supplies and establish an air bridge with Senegal. The first shipment of American equipment arrived late last week.

"The outbreak is such that more people will die," Obama said, "but the slope of the curve, how fast we can arrest the spread of this disease is within our control, and if we move fast, even if imperfectly, that can mean the difference between 10,000, 20,000, or 30,000 deaths rather than hundreds of thousands or millions of deaths."

The CDC estimates that the number of Ebola cases in West Africa could balloon to more than 550,000 unless a more robust response is mounted. However, the agency reported last week that if 70 percent of patients get treated soon to curb transmission, the outbreak could end by late January.

Last week, Obama announced he was sending up to 3,000 U.S. troops to West Africa to help with equipment, training and logistics to help control the outbreak.