They came from Egypt and Lebanon, Saudi Arabia and the UAE. Some were trained in bomb-making, some in hand-to-hand combat. Others were instructed in surveillance and reconnaissance. All of them learned the fine art of hiding in plain sight. They honed these and other skills in Afghanistan, where a fundamentalist group known as the Taliban had built a brutal, backward regime on the rubble of what the Soviet Union left behind. As they transformed their country into a torture chamber, the Taliban allowed Osama bin Laden to use Afghanistan as a terrorist campus—and a launching pad for his global guerilla war. On September 11, 2001, that war reached our shores.

Yet President Donald Trump’s envoys have been negotiating with the Taliban, finalizing what the White House calls a peace process, laying the groundwork for a “phased” withdrawal, and were even preparing to host the Taliban at Camp David. Trump says he plans to keep 8,600 troops in Afghanistan. But he is, as ever, mercurial about that, noting that he will “make a determination from there as to what happens...we're bringing it down”—and bringing it down fast. Within 135 days of signing a deal, Washington will withdraw 5,400 troops. Yes, Trump announced that he cancelled plans for Taliban emissaries “to secretly meet” him at Camp David. But with the 2020 election looming, there will be a strong incentive to restart the talks, drawdown to a fig-leaf force, and campaign on peace and prosperity.

Given that more than 60 percent of the public wants to withdraw from the land that spawned September 11, Trump is undeniably in step with the American people in this regard. As Trump’s predecessor liked to say, it’s “time to focus on nation-building here at home.” But if history is any guide, we will regret abandoning Afghanistan (again), trusting the Taliban and disengaging from the world around us.

Repeating

We’ve been here before. After the Soviets quit Afghanistan in 1988-89, Washington’s interest in that broken country declined dramatically. “As soon as the Soviets left Afghanistan, we turned our backs on Afghanistan,” former Defense Secretary Robert Gates recalls.

In 2009, leaders in the region implored Washington to resist the temptation to withdraw and instead “build on learning from the mistakes of the past.”

Neither the Obama administration nor the Trump administration showed much interest in learning from past mistakes.

Recall that President Barack Obama campaigned on a promise to withdraw from Iraq and made good on that promise in 2011. Obama always viewed U.S. involvement in Iraq as a problem to be corrected, rather than a commitment to be sustained. As former Defense Secretary Leon Panetta laments, the Obama White House was “so eager to rid itself of Iraq that it was willing to withdraw rather than lock in arrangements that would preserve our influence and interests.”

The Pentagon consensus was that Iraq needed the U.S. military to sustain the upward trajectory of the surge, to keep an eye on Iran and to keep a lid on al Qaeda in Iraq (which had been eviscerated by the surge). Frederick Kagan, chief architect of the surge, explained that “Painstaking staff work…led Gen. Lloyd Austin to recommend trying to keep more than 20,000 troops in Iraq after the end of 2011.” Before leaving his post as Joint Chiefs Chairman, Adm. Mike Mullen urged the White House to keep at least 16,000 troops in Iraq. “None of us recommended that we completely withdraw from Iraq,” according to Gen. Martin Dempsey (Mullen’s successor).

Predictably, without the steadying hand of the American military, sectarian tensions exploded; the window of opportunity for Iranian mischief widened; al Qaeda in Iraq reconstituted and rebranded itself as ISIS; Baghdad was nearly overrun; Yazidis, Shiites and Christians were massacred; and ISIS declared a jihadist state in the heart of the Middle East. Predictably, two years and six months after withdrawing American troops from Iraq, Obama rushed American troops back into Iraq.

“Under no circumstance should the Trump administration repeat the mistake its predecessor made in Iraq and agree to a total withdrawal of combat forces from Afghanistan,” Gen. David Petraeus advises. “A complete military exit from Afghanistan today would be even more ill-advised and risky than the Obama administration’s disengagement from Iraq.”

His solution: “The U.S. must retain its own means to pressure extremist networks plotting against the American homeland and U.S. allies,” which means “some number of American forces in Afghanistan, along with substantial enablers such as unmanned aerial vehicles and close air support.” Without such a force, he predicts “full-blown civil war and the re-establishment of a terrorist sanctuary as existed when the 9/11 attacks were planned there.”

Obama didn’t listen to such counsel regarding Iraq, and Trump isn’t listening regarding Syria and Afghanistan. This is no surprise. After all, Trump says, “Great nations do not fight endless wars.” Similarly, Obama said he was “was elected to end wars.” These twin sentiments have made for good politics, but they arguably reflect a misunderstanding of the commander-in-chief’s role in the constitutional order—especially in a time of war—and America’s role in maintaining international order. America has been engaged in “endless” missions in Germany since 1944, Japan since 1945, South Korea since 1950, Kuwait since 1991, Kosovo since 1999.

Regardless, elections have consequences, and there’s something to be said about trying to end war and make peace. However, in unilaterally trying to end the wars of 9/11, Trump and Obama have ignored a fundamental truth of human conflict: The enemy gets a vote. As Gen. James Mattis puts it, “No war is over until the enemy says it’s over.”

Trusting

That brings us to the issue of trust. To bring about a durable peace between two warring sides, one of two conditions must be met: Either one side concedes defeat (Imperial Japan on the Missouri), or both sides truly desire an end to hostilities (Sadat and Begin at Camp David).

The first kind of peace is a function of what happens on the battlefield, and is the byproduct of a simple calculus made by the party conceding defeat. The second kind of peace requires some modicum of trust between the warring sides. Neither condition has been met in Afghanistan.

The Taliban “controls or…contests almost half the country’s 407 districts,” according to U.S. military estimates. In addition, there are 20 foreign terrorist organizations, including al Qaeda and ISIS, at work in Afghanistan. Doubtless, some of them are collaborating with the Taliban. As Petraeus concludes, “The Taliban are far from defeated.”

Moreover, the Taliban have given us no reason to trust them to make good on their promises. Even as they talked peace in Doha, Taliban militants launched large-scale attacks in Kunduz and Kabul. (The Kabul attack was, apparently, what got Trump’s attention.) In late 2018, Taliban militants targeted and nearly killed the commander of U.S. and coalition forces in Afghanistan. A Taliban commander recently said, “We will continue our fight against the Afghan government and seize power by force.”

If that’s not enough, consider the Taliban’s record while in power and while trying to reclaim power: banishing girls from school, ordering Hindus to wear identity labels, destroying ancient Buddhist statues, summarily executing those belonging to opposing sects of Islam, depopulating areas controlled by ethnic minority groups, turning soccer stadiums into mass-execution chambers, burning people alive, jailing aid workers, beheading people for dancing, imprisoning foreigners who talked about Christianity, pouring acid on young women and teachers, using children to plant IEDs, making common cause with bin Laden.

How can we make a deal with people like that? Trump himself conceded as he cancelled the Camp David meeting, “What kind of people would kill so many in order to seemingly strengthen their bargaining position?” The answer can be found in the preceding two paragraphs. They haven’t changed, and they won’t change. To think a piece of paper or “peace process” will bring the Taliban into the political sphere and prevent them from doing the only thing they know to do is fantasy. Hopefully, the president now sees the Taliban for what it is.

Disengaging

Trump today and Obama before him are reflections of an America that is not just war-weary, but increasingly world-weary. Yet that reality doesn’t justify their course of action. Leadership—especially on matters of national security—sometimes requires more than reflecting the national mood. There are times when a president is called upon to explain to the American people why they should follow a path they would rather not take. Think about Jefferson abandoning a policy of appeasement and instead waging war on piracy half-a-world away; Lincoln transforming the Civil War from a struggle merely to preserve the Union into a struggle to abolish slavery; FDR dragging America back onto the world stage; Truman arguing for open-ended engagement and global containment of Moscow; Reagan reviving the nation’s flagging commitment to what Truman began; Bush 41 building support for the defense of Saudi Arabia and the liberation of Kuwait; Clinton wading into the Balkans; Bush 43 defending the surge.

America and its military have sacrificed much in Afghanistan—18 years; 2,435 dead; 20,516 wounded; around a trillion dollars. Trump, Obama and other well-meaning observers look upon these numbers and conclude that the costs are just too high—the costs of Afghanistan’s rehabilitation, the costs of America’s security, the costs of international order, the costs of engagement.

Without question, engagement carries heavy costs. The Cold War cost Americans 104,000 military personnel and $6 trillion. The war on terrorism has claimed 6,900 U.S. personnel and devoured $2 trillion in treasure.

Yet we hear little about the costs of disengagement: Nanking, Pearl Harbor and Auschwitz in the 1930s and 1940s; Korea in the 1950s; Afghanistan in the 1990s, which led to the maiming of Manhattan; Iraq in the 2010s, which gave rise to ISIS. And we often overlook the benefits of engagement. During the Cold War, U.S. engagement preserved free government, rehabilitated Germany and Japan, and transformed Europe from an incubator of war into a partnership of prosperity. During the war on terror, U.S. engagement has put the enemy on the defensive, prevented a second or third or fourth 9/11, forced the enemy to expend finite resources on survival, and pushed the battlefront away from our shores.

One of the hardest things for the American people to understand about the war unleashed by 9/11 is that, 18 years in, we are closer to its beginning than its end. To those who have been listening, this comes as no surprise. Just days after the 9/11 attacks, President George W. Bush tried to brace Americans for “a lengthy campaign unlike any other we have ever seen.” In October 2001, Adm. Michael Boyce, then-Chief of the British Defense Staff, posited that the war on terror “may last 50 years.” By 2004, U.S. generals were calling the campaign against terrorism “the long war.” Dempsey called the struggle against jihadism “a 30-year issue.” Indeed, in its duration, geopolitical and geographic scope, ideological dimensions, and economic and human costs, the war on terror is more akin to the Cold War than other wars in American history. Regrettably, two successive administrations have failed to grasp this, and hence failed to explain this to the American people.

Instead, Trump laments that “We’re almost a police force over there.” Perhaps that’s how we should look at Afghanistan. If America is unwilling to commit the resources to crushing the Taliban, then policing Afghanistan’s stubbornly-ungovernable land seems a prudent fallback, especially given what Afghanistan has spawned. “The cost of retaining a few thousand troops in Afghanistan pales in comparison with the price the nation will pay strategically and economically if al Qaeda or ISIS rebuilds a terrorist platform there,” Petraeus warns.

For a reminder of what that cost entails, take a look at the Manhattan skyline.

A version of this essay appeared in Providence.