Most recently, Mr. Trump last week announced that transgender Americans would be barred from military service — catching the Pentagon by surprise and upending a long-running internal review process. After each of these episodes, stories leak about how the generals were either outgunned by advisers like Stephen Bannon or, more often, just left out of the loop.
At the margins, the generals may dial back their boss’s impulses, and occasionally stand up to Mr. Trump in small ways, as Mr. Mattis did when he declined to praise Mr. Trump in a televised cabinet meeting in June. And there are small victories: Last week, General McMaster managed to remove the Flynn holdover Derek Harvey, the Middle East senior adviser and an Iran hawk, from the security council.
But it’s unlikely that the generals will consistently rein in Mr. Trump at the strategic level. Gen. Joseph Dunford Jr., the chairman of the Joint Chiefs of Staff and therefore, on paper at least, the president’s primary military liaison and adviser, rarely has one-on-one meetings with Mr. Trump. Mr. Kelly, a former Marine general who had served as his secretary of homeland security and whom many had hoped would temper the president on immigration, apparently shares Mr. Trump’s policy views and seems disinclined to challenge him. It’s unlikely he will change now that he’s chief of staff.
.. In the mid-1950s, the political scientist Samuel P. Huntington observed that American military officers had evolved into a disciplined and largely apolitical group of professionals. He outlined a separation of roles: military obedience to civilian leaders in areas of strategic or political discretion, and civilian deference to the military on operational matters.
This was the norm until after Vietnam, when numerous scholars conducting post-mortems on the war — including, coincidentally, General McMaster in his book “Dereliction of Duty” — concluded that military commanders should have challenged civilian leaders more aggressively.
And over time, that’s what happened. As the Pentagon gained a broader post-Sept. 11 mandate, branching into what were once considered law enforcement and diplomatic arenas, the line between the civilian and military division blurred. Combatant commanders’ assertiveness peaked when a beleaguered President George W. Bush looked to Gen. David Petraeus to extricate the United States from the Iraq quagmire by way of the “surge” in 2007.
.. Unlike Mr. Obama, who took responsibility for his administration’s military actions, Mr. Trump has publicly scapegoated the military for politically damaging episodes, such as the errant February raid in Yemen in which one Navy SEAL and up to 30 civilians died. He has also been openly at odds with Mr. Mattis over torture, budget cuts at the State Department and climate change.
.. General McMaster admitted that Mr. Trump went into his private meeting with President Vladimir Putin of Russia at last month’s G-20 meeting without an agenda — indeed, without General McMaster.
.. So where will the check on Mr. Trump’s incompetent foreign policy come from? Not the State Department, under siege and led, for now, by the underqualified Rex Tillerson. Only Congress, on a bipartisan basis, can constrain Mr. Trump’s recklessness and ineptitude.