Some heard a declaration of victory, others an admission of defeat. The many contradictions in President Obama’s speech about Afghanistan Wednesday night were perhaps intended to obscure the bottom line: Tens of thousands of American troops will remain for at least three more years, some of them will be maimed or killed, and Obama offered no good reason why.

The only debate within the administration, it appears, was whether to bring home the troops far too slowly or not at all. Obama decided on the too-slowly option.

A year from now, we will have withdrawn the more than 30,000 “surge” troops Obama ordered into combat 18 months ago. But this means nearly 70,000 U.S. troops will remain in Afghanistan — about double the number deployed there when Obama took office. A “process of transition,” in which Afghans take responsibility for the country’s security while Americans come home, is supposed to be complete in 2014. But it sounds as if some sort of considerable force will remain in a “support” role.

In other words, there will be three more years of war followed by a long-term presence of unspecified magnitude.

Why? After a decade of war, what can we possibly gain by slogging ahead?

In the speech, Obama gave a host of reasons to consider our mission in Afghanistan accomplished. Al-Qaeda’s leadership has been decimated. Osama bin Laden is dead. The Taliban has been ousted from power. The capacity of the freely elected, U.S.-backed Afghan government to fight the war — and perhaps, someday, to keep the peace — has grown by leaps and bounds.

“The goal that we seek is achievable,” Obama said, “and can be expressed simply: no safe haven from which al-Qaeda or its affiliates can launch attacks against our homeland or our allies.”

By that standard, we’ve succeeded. The troops can come home tomorrow — all of them.

If, on the other hand, the goal is to leave behind a country that can never be used as a terrorist base, then success is impossible. No such airtight guarantee could be made about Canada, let alone Afghanistan. Have the president and his generals forgotten that much of the planning for the Sept. 11, 2001, attacks took place in Germany?

“We won’t try to make Afghanistan a perfect place,” Obama said. That sounds reasonable — until you realize that the imperfect Afghanistan of 2014 will surely look like the imperfect Afghanistan of today.

Three years from now, the Afghan government will still be thoroughly corrupt. The Taliban will still have considerable support, based on ethnicity and kinship, in the Pashtun heartland. Distrust of central authority will still be a defining national characteristic.

We have already done all that is within our power to eliminate the terrorist threat that Afghanistan once posed. It is not within our power to impose lasting peace and prosperity. Obama acknowledged that this can be achieved only through a political settlement. But only Afghans can make — and keep — such a deal.

In essence, we are using military means to pursue political ends that lie beyond our reach. Obama should realize that this makes no earthly sense.

Perhaps the most disheartening thing about Obama’s speech was the absence of fresh thinking, or even clear thinking. It was hard to tell whether he was sticking with his counterinsurgency strategy or switching to a counterterrorism approach — or, perhaps, doing a little of both. There was no evidence he had considered the possibility that the war is being perpetuated not by rational pursuit of our national interests but by its own inertia.

Nor was there any indication that he had thought through the mellifluous passages designed to put the war into a broader foreign policy context. We cannot “retreat from our responsibility” but also cannot be “overextended,” and therefore we must “chart a more centered course.” We must be “as pragmatic as we are passionate, as strategic as we are resolute.” If you have any idea what this means, please let me know.

Obama did say that when military intervention is called for, it should be international rather than unilateral. As an example, he cited Libya, where NATO is nominally in charge. He must have missed the speech by his outgoing defense secretary, Robert Gates, who warned that NATO is devolving into a toothless joke.

The president was crystal clear on just one point: For now, the war goes on.

eugenerobinson@washpost.com