Defense Secretary Lloyd J. Austin III has ordered six commercial airlines to provide passenger jets to help with the growing U.S. military operation evacuating Americans and Afghan allies from Kabul, the Afghan capital, the Pentagon said on Sunday.Mr. Austin activated Stage 1 of the Civil Reserve Air Fleet, created in 1952 after the Berlin airlift, to provide 18 airliners to help ferry passengers arriving at bases in the Middle East from Afghanistan, John F. Kirby, the Pentagon spokesman, said in a statement.The current activation is for 18 planes: four from United Airlines; three each from American Airlines, Atlas Air, Delta...