Air Force

FILE - In this Feb. 11, 2019, photo, acting Defense Secretary Patrick Shanahan, left, arrives in Kabul, Afghanistan to consult with Army Gen. Scott Miller, right, commander of U.S. and coalition forces, and senior Afghan government leaders. Shanahan, the former Boeing executive, was in a familiar place, aboard an airplane, when he got word of a bolt-from-the-blue political shot across his bow. A key senator seemed to have buried Shanahan’s chances of being nominated as the next secretary of defense. The crisis passed, but it highlighted the precarious position Shanahan occupies as he waits for President Donald Trump to decide who he will successor to Jim Mattis as leader of the Pentagon. (AP Photo/Robert Burns)

President Donald Trump pauses during a signing event for "Space Policy Directive 4" in the Oval Office of the White House, Tuesday, Feb. 19, 2019, in Washington. (AP Photo/ Evan Vucci)

An United States Air Force C-17 cargo plane loaded with humanitarian aid lands at Camilo Daza airport in Cucuta, Colombia, Saturday, Feb. 16, 2019. The U.S. Air Force has begun flying tons of aid to the Colombian town on the Venezuelan border as part of an effort meant to undermine socialist President Nicolas Maduro. (AP Photo/Fernando Vergara)

This image provided by the FBI shows part of the wanted poster for Monica Elfriede Witt. The former U.S. Air Force counterintelligence specialist who defected to Iran despite warnings from the FBI has been charged with revealing classified information to the Tehran government, including the code name and secret mission of a Pentagon program, prosecutors said Wednesday, Feb. 13, 2019. (FBI via AP)

In this Tuesday, Dec. 18, 2018 photo, Michele Fitzpatrick, a retired lieutenant commander in the Coast Guard, poses for a photograph at the United States Coast Guard Academy in New London, Conn. Female veterans, both current and former service members, were more likely to vote in the 2018 midterm elections for Democrats than Republicans, 60 percent to 36 percent, according to data from VoteCast. (AP Photo/Jessica Hill)

President Donald Trump and first lady Melania Trump arrive for a Christmas Eve service at the National Cathedral, Monday, Dec. 24, 2018, in Washington. (AP Photo/Jacquelyn Martin)

FILE - In this April 9, 2018, file photo, Deputy Secretary of Defense Patrick Shanahan, right, listen as President Donald Trump speaks during a cabinet meeting at the White House, in Washington. A U.S. administration official says that Defense Secretary Jim Mattis will leave his post Jan. 1, 2019, as Trump is expected to name Shanahan as acting secretary. (AP Photo/Evan Vucci, File)