America has been at war in Afghanistan for more than 13 years. U.S. troop levels peaked at 140,000 in 2010. More than 2200 Americans died in a conflict reflecting little more than purposeless inertia.

The U.S. is leaving, but not entirely and maybe not soon. Warned NATO commander Gen. Philip Breedlove in January, “we are going to continue to have casualties.” The formal combat mission might be over, but combat is not.

Roughly half of the 10,600 American troops are supposed to depart by the end of the year, with the rest scheduled to go in 2016. But the administration is considering slowing the withdrawal.

Washington intervened in Afghanistan with two overriding objectives: destroy al-Qaeda and oust its Taliban hosts. The U.S. quickly fulfilled both goals. But then the Bush administration lost interest in the country.

Instead of ending Washington’s half-hearted misadventure at nation-building, the Obama administration twice doubled down. Some progress was made, but when I visited I found only limited confidence in private.

Washington and its allies built a large government bureaucracy and security force in Kabul, but on a potential foundation of sand. The Afghan government is noted for venality, incompetence, and corruption.

The administration celebrated Ashraf Ghani’s election since he signed the (U.S.) Bilateral Security Agreement and (NATO) Status of Forces Agreement which Hamid Karzai had rejected. This allowed Washington to retain around 10,000 Americans (joined by roughly 3000 Europeans) in the Afghan muddle.

These forces are not necessary to confront al-Qaeda, which largely has disappeared from Afghanistan. Little likely would change if the Taliban again dominated the country: the group learned that misbehaving foreign guests bring down the wrath of a superpower.

Some policymakers hope to leave a liberal, democratic outpost in Central Asia. Unfortunately, Afghanistan’s gains are fragile and failures are significant.

Tens of tens of thousands of troops, thousands of lives, hundreds of billions of dollars, and thousands of aid projects from America failed to fix the country. A much smaller U.S. troop presence won’t remedy the system’s deep deficiencies.

Afghanistan still could eventually end up with a reasonably liberal society, but only on its own terms. Thankfully, what emerges won’t be matter much to America so long as Afghanistan does not host terrorists bent on striking the U.S. The conflict has regional impacts, but none of significant consequence to America.

Surrounding countries likely will play the Great Game as Washington’s force levels drop. But U.S. security is not dependent on Central Asian stability.

America’s most important task may be to use its remaining time to encourage resumption of talks between the Afghan government and Taliban. There should be no illusions about the prospect of success.

Of course, Washington hopes to forestall a Taliban victory. But last year was the costliest for the Afghan National Security Forces since the conflict began in 2001. The Diplomat’s Franz-Stefan Gady reported: “There are areas that are a no-go for the ANSF, others where they will only go with U.S. air support, and others where they will go on their own,” mostly major urban areas.

Kabul’s main hope is Taliban weakness. The movement’s brutality has cost support. The United Nations noted “divisions driven primarily by differences over political strategy” as well as factions behaving “with increasing autonomy.” The Taliban also faces violent competition from groups claiming allegiance to the Islamic State.

Afghanistan is most likely to end up with multiple “governments.” Which gives everyone an incentive to reach a modus vivendi to end the fighting. Even Pakistan, after long backing the Taliban, may be ready to encourage negotiations.

The administration should live up to its promise to leave Afghanistan. Thirteen years of war is more than enough. Washington also should abandon its attempts at global social engineering.

As I wrote on Forbes online: “Afghanistan is a tragedy. Unfortunately, that isn’t about to change. It is time for America to leave. Some day Afghanistan must stand on its own. That day should be today. Only Afghans can decide Afghanistan’s destiny.”