The U.S. military intervention in Afghanistan is now well into its sixteenth year, making it America’s longest foreign war. Worse, there is no end in sight. In fact, military leaders are trying to convince President Trump to escalate U.S. involvement once more by sending several thousand additional troops into the fray. Pundits and foreign-policy commentators are engaged in a cottage industry to formulate yet more strategies to make the Afghanistan mission finally succeed.

There has been an American military presence in that unhappy country for so long that it is sometimes difficult to remember that the original purpose was both focused and limited. U.S. leaders justified the initial invasion in October 2001 as a necessary response to the 9/11 terrorist attack on the United States. Foreign fighters belonging to Al Qaeda had used the country as a safe haven and base of operations to plan and execute their devastating assault. The Taliban government of Mullah Omar had treated Osama bin Laden and his followers as honored guests, enabling them to carry out their plans.

That behavior caused a decisive change in U.S. policy toward Kabul. American officials had always viewed the Taliban regime with understandable distaste, given its treatment of women, the desecration of irreplaceable historical monuments, and the overall brutal, reactionary policies. But Washington did not view the Taliban itself as a security threat that warranted U.S. intervention—until the regime became an enabler to Al Qaeda.

In the weeks after the 9/11 attacks, U.S. officials repeatedly stressed that defeating Al Qaeda—and, if possible, killing or capturing Bin Laden—was the primary objective. Overthrowing Omar’s government was not initially a stated goal. Washington did demand, however, that Kabul sever its ties with Al Qaeda and turn over Bin Laden and the other leaders to the United States. Only when Omar rejected those demands, did Washington pursue forcible regime change. Even then, U.S. leaders did not advocate a long-term war against that indigenous Afghan faction, however odious its social policies might be.

The United States did engage in military cooperation with the Northern Alliance, the principal armed faction opposing the government in Kabul, when Washington launched the invasion of Afghanistan. Tactically, the association with the Northern Alliance paid off. Alliance personnel provided most of the ground forces while the United States supported them with devastating air power. Their joint offensive ousted the Taliban in a matter of weeks.

The tactical cooperation, though, began to entangle America in the country’s complex ethnic and tribal politics. The Northern Alliance consisted primarily of fighters from the Tajik and Uzbek ethnic communities. Conversely, the Pashtuns, Afghanistan’s largest single ethnic bloc dominated the Taliban.

Washington’s successful military operation led to the installation of Hamid Karzai, one of the minority of Pashtuns willing to collaborate with the Northern Alliance, as president. The Pentagon retained its emphasis on disrupting Al Qaeda and tracking down bin Laden and the other leaders. With greater cooperation from the government of Pakistan, the U.S.-led offensive might have succeeded in that task as well, but Islamabad allowed Taliban fighters to escape across the ill-defined border into Pakistan. Even then, had the Pentagon not begun to shift its focus to preparing for the invasion of Iraq, U.S. forces might still have succeeded in decapitating the Taliban leadership. Despite those annoying limitations, the U.S. military campaign badly weakened the terrorist organization.

During the years immediately following the 2001 invasion, American officials and the news media concentrated on Al Qaeda and the threat it posed. Mentions of the Taliban were far less frequent, and they usually seemed little more than an afterthought. That emphasis began to change in 2004 and 2005. Increasingly, official statements and media accounts portrayed the Taliban as America’s primary enemy in Afghanistan. References to Al Qaeda diminished to the point that some wags began to call the terrorist leader “Osama bin Forgotten.” There was a good reason for that fading of attention. When pressed, U.S. officials and members of Congress, then and in subsequent years, conceded that there were no longer more than a few dozen Al Qaeda operatives remaining in Afghanistan. Most of what was left of the group was across the border in Pakistan. And, indeed, when U.S. forces finally located and killed bin Laden, he was in Pakistan, residing within a few hundred yards of a Pakistani military command center.

The 2004–05 period was the crucial point that the U.S. war in Afghanistan shifted from a counterterrorism campaign against Al Qaeda to a counterinsurgency campaign against the Taliban, combined with an ambitious nation-building venture to transform Afghanistan into a modern, democratic society. For the American people, that change amounted to a foreign-policy version of “bait and switch.” And the change was certainly not beneficial. By the end of 2013, Washington had spent more than $116 billion in nonmilitary aid to Kabul—money that was mostly wasted on impractical projects or stolen by corrupt Afghan officials.

The counterinsurgency/nation-building effort has grown steadily more futile over the years. The Obama administration tried to salvage matters by agreeing to the Pentagon’s recommendations to escalate the war with the deployment of additional U.S. military personnel. Obama acquiesced, sending seventeen thousand troops in early 2009 and another thirty thousand troops later in the year, bringing the overall United States total to one hundred thousand. But the situation did not improve significantly. About the only clear result is that U.S. casualties spiked. A 2014 study found that 74 percent of U.S. military fatalities in the Afghan war had occurred since Obama ordered the escalation. Obviously, that percentage has gone up since then. Although the president gradually withdrew those additional forces, several thousand American troops still remain in that volatile setting, with more likely on the way.

The Afghan government—under both Karzai and his successor, Ashraf Ghani—remains a cesspool of corruption and ineffectiveness. Indeed, despite talk of a cooperative, united government, the regime is effectively divided between Ghani and his chief political rival, “Chief Executive Officer” Abdullah Abdullah. Meanwhile, the Taliban continues to gain ground in the heavily Pashtun southern and eastern portions of the country, and has been able to launch devastating attacks against Kabul—and even Uzbek and Tajik targets in the north. The feckless Afghan national army has so clearly failed to halt that trend that Pentagon officials are pressing the Trump administration to send another contingent of U.S. troops to bolster those forces.

That request is a tacit admission that there is no end in sight to the sixteen-year war that has already claimed more than 2,400 American lives and more than $1 trillion tax dollars. There are no legitimate American strategic or economic interests in Afghanistan to warrant such sacrifices—much less to make additional ones.

Entangling the United States in a murky civil war was a colossal foreign-policy blunder. A punitive expedition to damage, if not fatally weaken, Al Qaeda was a proper response to 9/11. Getting mired in parochial feud between the Taliban and the sleazy, corrupt regime in Kabul was not a proper—or intelligent—response. Washington had achieved its legitimate security objectives in disrupting Al Qaeda by 2005. Certainly, managing to kill Bin Laden in 2011 should have eliminating any lingering justification for staying in Afghanistan.

Making the Taliban the primary enemy has gotten the United States into an unwinnable war. Al Qaeda fighters were foreigners (primarily Arabs) who were resented by most Afghans. The Taliban, on the other hand, is a powerful faction within Afghanistan’s largest ethnic group—the Pashtuns. We are now not only trapped in the middle of a civil war in Afghanistan, but a parochial power struggle within the dominant ethnic faction. Both the Taliban and much of the leadership in Kabul is Pashtun. Perhaps even worse, Washington has embarked on a quixotic nation-building venture that would have enthused Woodrow Wilson.

How such an interminable crusade benefits the genuine security interests of the United States should be mystifying to all Americans. Although the public endorsed a punitive war against Al Qaeda, it was never asked to sign-up for a crusade against the Taliban—much less for a quest to bring modernity, democracy and gender equality to Afghanistan through military force. Yet that is what the Afghan intervention has become. The Trump administration should move to terminate that multi-year exercise in foreign-policy masochism immediately.

Ted Galen Carpenter, a senior fellow in defense and foreign-policy studies at the Cato Institute and a contributing editor at the National Interest, is the author of ten books, the contributing editor of ten books, and the author of more than 650 articles on international affairs.

Image: Marines fire an M777A2 lightweight howitzer during a field fire in Helmand Province. Flickr/U.S. Central Command