President Obama’s decision to send another 30,000 U.S. troops to Afghanistan during the next six months does not make sense. Hardly anybody has real enthusiasm for the plan. Both Democrats and Republicans in Congress are lukewarm, for the most part; some are stridently opposed. The military chiefs apparently support the plan, but surely the president can appease them in alternative, less politically risky ways.

In explaining his plan, the president declares that “we must deny al-Qaida a safe haven. We must reverse the Taliban’s momentum . . . And we must strengthen the capacity of Afghanistan’s security forces and government” because “it is from here that we were attacked on 9/11, and it is from here that new attacks are being plotted.” If these statements express the president’s actual thoughts, then he is much less astute than he is usually given credit for.

Al-Qaida—if such an organization may be said to exist as anything more than a sprawling, loosely articulated collection of hyper-zealous, anti-American Muslims—does not need Afghanistan to plan and mount attacks against the United States and U.S. allies. Such terrorists may spring, as they have sprung, from many places. They have emerged in Indonesia, Turkey, Spain, and Germany, as well as in Afghanistan, Pakistan, Saudi Arabia, and other Middle Eastern venues. Even if U.S. forces held Afghanistan in an iron grip—an unachievable condition—the security of Americans in America would not be appreciably enhanced. In short, subduing U.S. opponents in Afghanistan is a low-yield investment, at best.

More likely, it is a losing investment. Opposition to the U.S. forces and their Afghan puppets arises for the most part from the deeply entrenched tribal character of the Afghan people and their implacable desire to rid the country of any and all foreign occupiers. One need not have studied the history of the place for a lifetime to have learned this lesson.

Making his Big Push idea even more impenetrable, the president promises that eighteen months after the buildup is completed, the troops will begin to be withdrawn. Does anyone really imagine that the Taliban and other anti-American groups in Afghanistan are too stupid to sit tight and wait for the foreign devils to depart? If these groups are anything, they are in the fight for the long haul. They can afford to be patient.

As in other occupied countries, U.S. authorities declare that they will accomplish their mission by building up “legitimate” government troops and police, by training and equipping them until they are strong enough to whip the insurgents. This plan is no more promising in Afghanistan than it was in Vietnam. The problem is not that the “legitimate” side is not strong enough or trained well enough to defeat the “bad guys.” The pro-U.S. Afghans have only been rented for as long as the dollars keep flowing. U.S. policy makers talk as if they lack the wit to comprehend these elementary facts.

Obama’s Big Push looks like a military analogue to the basic economic mistake of throwing good money after bad. The more than 800 American servicemen who have already died in Afghanistan cannot be brought back to life. The vast sum of money expended, so far with absolutely nothing of genuine worth to show for it, represents forgone opportunities forever sacrificed.

A clear-thinking president would steer clear of trying to accomplish the impossible. The war in Afghanistan is not winnable in any meaningful sense. It’s a pure waste, suffered at a time when the American people have a multitude of more urgent needs. To curtail their losses, the Americans should get out of Afghanistan immediately.