KABUL, Afghanistan — Last year, when President Trump announced a new strategy 16 years into the Afghan war, many in Afghanistan saw it as a much-needed refocusing of the American commitment.

“Conditions on the ground — not arbitrary timetables — will guide our strategy from now on,” Mr. Trump said at the time. “America’s enemies must never know our plans or believe they can wait us out.”

In the year since then, as the architects of that strategy have exited the administration one by one, many in Afghanistan came to believe that Mr. Trump — who never met with his former top commander in the country — had never really been persuaded, and that his impatience with the war was winning out.

On Friday, that suspicion seemed to be confirmed, as Afghan officials and Western diplomats woke to the unexpected news that Mr. Trump had ordered half of the 14,000 American troops in Afghanistan home, even as the war continues to rage and the Taliban threaten much of the country.