Then came the years after Sept. 11. The specter of torture, like the treatment of detainees at black sites and the detentions at Guantánamo, crystallized a moral sensibility according to which it mattered most to dissidents within George W. Bush’s administration as well as a growing chorus of critics outside not where war went and how long it lasted but whether the laws governing the conduct were respected.
In the wake of the release of the Abu Ghraib photos in April 2004, humanitarian concern helped remove the bug of torture and other indignities from the program of endless war, thereby rebooting it: After all, a critique of a war focused on its egregious conduct can lead to a different and improved version of that war, rather than its end. That is precisely what happened.
In the first years of his presidency, Barack Obama capitalized on the emphases of the years just before. After running as a peace candidate in 2008, he promised in his critical first months to treat prisoners well and earned plaudits for doing so. His administration deleted noxious memos permitting torture and left the ones permitting war.
But it is easier not to mistreat prisoners if you no longer capture them. Mr. Obama vastly expanded the war on terror in scope, taking it beyond the two countries on which Mr. Bush had focused to more than 10, relying on drone strikes and special forces raids. He also went beyond Mr. Bush in formalizing a humane framework for endless war, announcing in policy that it was not the brutal war of the past but one corrected by the new sensibility.
Astonishingly, Mr. Obama even went beyond what the new laws of war required, promising never to strike off battlefields if there was any risk of collateral damage, a standard that was revealing of a new moral sensibility even if it was — like so many such rules — never adhered to in practice.
In his Nobel Peace Prize address at the end of his first year as president, Mr. Obama offered an almost metaphysical case for America fighting forever, while promising to do so humanely: “We must begin by acknowledging the hard truth: We will not eradicate violent conflict in our lifetimes,” he explained. But its humane conduct was “a source of our strength.”
To a striking and unanticipated extent, the humanization of American might is something even President Donald Trump was forced to retain. True, he called in 2016 to “bring back waterboarding,” but to the extent that he tried, he was held in check. (“He better bring his own bucket,” Michael Hayden, the former director of the C.I.A., remarked.) And while Mr. Trump decreased transparency around drone strikes and loosened top-down authority, other humane requirements largely remained in place.