Show of hands: Does anybody really understand the U.S. policy in Afghanistan? Can anyone figure out how we’re supposed to stay the course and bring home the troops at the same time?

I’m at a loss, even after President Obama’s surprise trip to the war zone. The president’s televised address from Bagram air base raised more questions than it answered. Let’s start with the big one: Why?

According to Obama, “the United States and our allies went to war to make sure that al-Qaeda could never use this country to launch attacks against us.” I would argue that U.S. and NATO forces have already done all that is humanly possible toward that end.

The Taliban government was deposed and routed. Al-Qaeda was first dislodged and then decimated, with “over 20 of their top 30 leaders” killed, according to the president. Osama bin Laden was tracked to his lair in Pakistan, shot dead and buried at sea. To the extent that al-Qaeda still poses a threat, it comes from affiliate organizations in places such as Yemen and from the spread of poisonous jihadist ideology. Al-Qaeda’s once-extensive training camps in Afghanistan have long been obliterated, and the group’s presence in the country is minimal.

That smells like victory to me. Yet 94 American troops have lost their lives in Afghanistan so far in 2012, U.S. forces will still be engaged in combat until the end of 2014, and we are committed to an extraordinary — and expensive — level of involvement there until 2024. Why?

Of the U.S. troops who died this year as a result of hostile fire — as opposed to accidents, illnesses or suicide — at least one of every seven was killed not by the Taliban but by ostensibly friendly Afghan security forces.

A report by military and political behavioral scientist Jeffrey Bordin, commissioned by the Pentagon last year and now classified, concluded that “the rapidly growing fratricide-murder trend” of attacks by Afghan soldiers and police against U.S. and allied troops reflects “the ineffectiveness in our efforts in stabilizing Afghanistan, developing a legitimate and effective government, battling the insurgency [and] gaining the loyalty, respect and friendship of the Afghans.”

Policies such as nighttime raids, in which civilians have been killed, and incidents such as the burning of Korans by allied soldiers have generated increasing resentment in a country that has never taken kindly to foreign occupation.

These friendly-fire killings are not just isolated incidents, the report says, but a “continuing pattern” that is leading to a “crisis of trust” between allied and Afghan forces. Unless there is reform of “profoundly dysfunctional Afghan governmental systems and key leaders,” the report predicts, “any efforts in developing a legitimate, functional and trustworthy Afghan army and police force will continue to be futile.”

It should be noted that U.S. commanders in Afghanistan strongly disagree. They express confidence that the Afghan army is becoming a much more competent and professional fighting force. But they acknowledge that the process requires time and a continuing commitment of troops and funding.

As Obama knows, however, polls indicate that Americans are weary of this war. He told the nation Tuesday night that 23,000 troops would be withdrawn by the end of the summer. This will reduce troop levels to about 65,000 — still far above what Obama inherited in 2009. By the end of 2014, Obama said, “the Afghans will be fully responsible for the security of their country.” But how many Americans will remain? And, again, why?

At that point, Obama said, we will leave behind just enough personnel to support the Afghan government in counterterrorism operations and provide continued training for Afghan forces. At present, however, we’re in the midst of a counterinsurgency campaign of the kind that takes decades, at best, to succeed. If we’re going to switch to counterterrorism in a couple of years, why not just make the switch now?

Another question: Obama said we will establish no permanent bases in Afghanistan. But the agreement he signed with Afghan President Hamid Karzai gives the United States continuing use of bases that we built and intend to transfer nominally to Afghan control. What’s the difference?

The United States has agreed to support Afghanistan’s social and economic development and its security institutions through 2024. Does this sound like nation-building to you? Because that’s what it sounds like to me.

“Tonight, I’d like to tell you how we will complete our mission and end the war in Afghanistan,” Obama said Tuesday. We’re still waiting.

eugenerobinson@washpost.com