WASHINGTON — In the early days of the Trump administration, national security officials began exploring ways to free Austin Tice, an American journalist and a former Marine officer believed to be held by the Syrian government. His case has frustrated investigators and diplomats since he disappeared while on assignment nearly five years ago.
White House officials decided, because of the delicacy of the situation, to set up a back channel. Given the deteriorated relations between the United States and Syria, options were limited. So in early February, Mike Pompeo, the C.I.A.