Today’s high schoolers don’t know a time when the United States was not at war in Afghanistan. Conservative estimates find that U.S. taxpayers have spent almost $1 trillion in the country since 2001. Of this amount, $126 billion has gone toward Afghanistan reconstruction — more in inflation‐​adjusted dollars than was spent to rebuild Europe after World War II. At least another $750 billion has been spent on warfighting. Despite such efforts, the Taliban controls more territory than at any time since the war began. It is obvious that reversing these trends would require a level of effort that Americans will not abide.

President Trump was correct, therefore, to call attention in his State of the Union address to the “constructive talks” that his administration was engaged in “with a number of Afghan groups, including the Taliban.”

Presidential envoy Zalmay Khalilzad, a former ambassador to Afghanistan and Iraq, reported last week that the negotiators had agreed in principle to a framework to end the war.

“As we make progress in these negotiations,” President Trump explained, “we will be able to reduce our troop presence and focus on counter‐​terrorism.” On another occasion in the speech, he stated, succinctly, “Great nations do not fight endless wars.”

The editorial board of the New York Times – not normally thought of as a Trump ally – has reached a similar conclusion: “The troops have fought bravely in Afghanistan. It’s time to bring them home.”

A number of the president’s critics, however, disagree. The Brookings Institution’s Michael O’Hanlon, for example, claimed late last month that it “would be a mistake” to reduce the American military presence in Afghanistan. “There is still a strong case,” he wrote in the New York Times, “to sustain America’s longest war.”

Former U.S. ambassador to Afghanistan, Ryan Crocker, equated a negotiated withdrawal to surrender. He urged the United States to pledge to leave U.S. troops “in Afghanistan as long as the current government wants them.”

In this case, at least, Trump is correct, and his critics are not: a negotiated end to the war in Afghanistan, and the removal of all U.S. forces from the country in a deliberate but expeditious fashion, is in our national interest. Remaining there indefinitely would be folly.

A U.S. military presence in Afghanistan is no longer necessary. Leaving U.S. troops there, without an achievable mission, and with no timetable for achieving it, is also deeply unpopular. A recent poll, for example, found that a majority of Americans would support a decision to remove all U.S. troops from Afghanistan within a year, while only 22 percent would oppose such a move.

To be sure, the decision to go into Afghanistan after 9/11 was justifiable. The object should have been to destroy the terrorist training camps in the country, to remove the terrorist‐​harboring Taliban government, and to send a clear message to others that such behavior would no longer be tolerated. If the Bush administration had defined its post‑9 /11 goals appropriately, U.S. forces could have left soon after the post‐​Taliban government under Hamid Karzai was installed in Kabul. 

The counterterrorism rationale for remaining in Afghanistan 17 years after 9/11, however, doesn’t hold water. After all, as the Times’ editorial noted, “the initial American objective — bringing Bin Laden to justice — has been achieved. And subsequent objectives, to build an Afghan government that can stand on its own, protect the population and fight off its enemies, may not be achievable, and certainly aren’t achievable without resources the United States is unwilling to invest.”

Millions of Americans were attracted to Donald Trump’s instinct to get the United States out of foreign wars; indeed evidence suggests that it helped him in three electorally critical states – Pennsylvania, Michigan, and Wisconsin – in November 2016. Since then, however, Trump has mostly expanded the conflicts he inherited, and he has engaged in other actions, including with respect to Iran and Venezuela, that bring us closer to new ones. His decision to surge additional U.S. forces into Afghanistan in August 2017 was a serious mistake, on the merits, as well as a dramatic betrayal of one of his most important campaign promises.

Last night’s speech, therefore, could signal a key turning point of Trump’s presidency, at least as it pertains to the longest of the nation’s seemingly endless wars.

Let’s hope so.