US President Barack Obama said on Thursday that there was still a 'significant gap between where we are and where we need to be' in the international response to the deadly Ebola outbreak in West Africa. 'Stopping Ebola is a priority for the United States,' he told a meeting on Ebola on the sidelines of the UN General Assembly in New York. 'More nations need to contribute critical assets and capabilities - whether it's air transport, medical evacuation, health care workers, equipment, or treatment,' he said.