But its effect was unmistakable: He had outsourced the decision on how to proceed militarily in Afghanistan to the Pentagon, a startling break with how former President Barack Obama and many of his predecessors handled the anguished task of sending Americans into foreign conflicts.
“What we are seeing now is that the president has acknowledged that the Afghan mission is important, and we ought to do it right,” said James Jay Carafano, a national security specialist at the conservative Heritage Foundation who advised Mr. Trump’s presidential transition.
White House officials say they are still debating America’s role in Afghanistan — one senior adviser said they would consider issues as basic as whether the country needs a strong central government, rather than the warlords who have historically divided power there.
“The president doesn’t have the time or interest to make these decisions, so they want to leave the decision-making to Mattis,” said Richard H. Kohn, a military historian at the University of North Carolina at Chapel Hill who advised General McMaster on his doctoral thesis.
Officials said it would include diplomacy with Pakistan, India and even Iran, a nation that American diplomats cooperated with during the early months of the Afghan war but that the White House now sees as a bitter foe.