Liberia's Ebola cases double every 2 weeks

(CNN) – What started as a regional crisis is now being cast as a threat to health and security around the world.

Today, President Obama warned global leaders at the United Nations General Assembly that without quick action, the Ebola outbreak could become a humanitarian catastrophe.

The hardest hit nations are Sierra Leone and Liberia, where the number of cases is doubling every two weeks.

The explosive pace of this outbreak is overwhelming government and health workers in the region, Liberia's foreign minister Augustine Kpehe Ngafuan tells CNN's "The Lead with Jake Tapper." Check out his interview in the video above.