David WelnaDavid Welna is NPR's national security correspondent.
Mark Sandy, from the Office of Management and Budget, arrives to the U.S. Capitol earlier this month for a deposition regarding whether President Trump ordered a hold on military assistance to Ukraine.
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A U.S. military vehicle drives past an oil pump jack in the countryside of Syria's northeastern city of Qamishli. President Trump is leaving some U.S. troops in Syria, with the goal of controlling Syria's oil fields. But legal experts say exploiting the oil could amount to pillaging — a war crime.
Delil Souleiman/AFP/Getty Images
In this Oct. 23, 2018 file photo, Defense Secretary Jim Mattis speaks beside President Donald Trump, during a briefing with senior military leaders in the Cabinet Room at the White House in Washington.
Manuel Balce Ceneta/AP