The longest war in American history drags on, with Washington a captive of purposeless inertia. The Obama administration should bring all U.S. forces home from Afghanistan and turn the conflict over to the Afghans.

After Afghan-based terrorists orchestrated the 9/11 terrorist attacks, the Bush administration had little choice but to make an example of the Taliban regime as well as target al-Qaeda.

But the lesson that governments which allow terrorist attacks on America lose power was delivered 12 long years ago. The Bush administration soon switched to nation-building in Central Asia.

President Barack Obama then made the war his own, twice increasing the number of troops in Afghanistan. Still, he promised that U.S. forces would return home in 2014.

But now the administration wants to keep between 8,000 and 15,000 troops on station for years if not forever. The newly negotiated Bilateral Security Agreement would run until “the end of 2024 and beyond.”

Why? Afghanistan never was vital to America. Not even during the Cold War, when after the Soviet invasion in December 1979 the conflict offered a convenient and inexpensive (for Washington, not the Afghan people) opportunity to bleed Moscow dry.

As I point out in my latest Forbes online column:

Osama Bin Laden again focused U.S. attention on Afghanistan, but only the transitory terrorist connection made control of Kabul critical to America. With the displacement of al-Qaeda and punishment of the Taliban, Afghanistan quickly receded in importance. Observed Vice President Joe Biden: “we went there for one reason: to get those people who killed Americans, al-Qaeda. We’ve decimated al-Qaeda central. We have eliminated Osama bin Laden. That was our purpose.

So what is Washington doing there today? A mix of nation-building, democracy-promotion, and humanitarian intervention.

However, if the Afghan political system is not stable after years of allied military and financial support, the few thousand personnel the Obama administration hopes to keep in country won’t make much difference. Moreover, war is a dubious humanitarian tool. Afghanistan has been ravaged by decades of conflict.

Why else should Washington stay in Afghanistan? The country’s travails are destabilizing its neighbors, most obviously Pakistan, but the conflict is the most harmful factor. Continuing war after a U.S. withdrawal could affect other local powers, but the price of conflict without America is likely to remain far less than with America.

Lastly, when I visited Afghanistan in 2010 and 2011, allied officials justified the Western presence as being necessary to prevent an al-Qaeda revival. However, terrorists don’t need to locate in Afghanistan when they can operate in Pakistan and many other nations.

Moreover, even a triumphant Taliban wouldn’t likely welcome back the group which brought down the wrath of America. Indeed, concluded a Washington Post story on administration deliberations: “Many of the groups that U.S. forces target in Afghanistan—most notably the Afghan Taliban—do not appear eager to attack Americans or U.S. interests outside the country.”

The strongest argument against the “zero option” of no troops is that it would limit Washington’s capability to strike elsewhere, most notably in Pakistan. However, the administration’s proposed deployment looks more configured to act in the civil war that is likely to continue.

Further, the larger the projected presence, the greater the target for terrorists, insurgents, and other malcontents. Better a much smaller counter-terrorist operation, perhaps off-shore, as with Yemen.

Moreover, Washington should scale back its drone operations in Pakistan and elsewhere. So-called “signature” strikes, in which most anyone in proximity to suspected terrorists is viewed as a likely terrorist, undoubtedly kill locals who threaten no one. Further, the U.S. began targeting the Pakistan Taliban apparently on the rationalization that Pakistani militants might threaten Americans in Pakistan, leading to blowback with the PT targeting Americans.

Now, however, President Karzai says he does not want to sign the BSA until after April’s presidential election. He may be primarily engaged in extortion, having explained: “We want the Americans to respect our sovereignty and be an honest partner. And bring a lot of money.”

President Karzai’s chutzpah is in America’s interest. Because of him, U.S. troops actually might leave Central Asia—as they should.

Americans have been fighting in Afghanistan for longer than the Civil War, World War I, and World War II combined. It’s time for America to go home.