The U.S. forces will take over air traffic control at Kabul airport, in addition to expanding security there, the U.S.  Departments of State and Defense said in a joint statement Sunday.

"Tomorrow and over the coming days, we will be transferring out of the country thousands of American citizens who have been resident in Afghanistan, as well as locally employed staff of the U.S. mission in Kabul and their families and other particularly vulnerable Afghan nationals," said the statement.