During the Vietnam War, Sen. George Aiken, a Vermont Republican, was famous for suggesting that we declare victory and go home. (What he actually said is a little more nuanced, but that was the popular perception.)

President Obama seems to be pursuing a version of this strategy in Afghanistan. At least that is the inference one can draw from his claims of success at a news conference with Afghan President Hamid Karzai in which the two leaders unveiled an acceleration of the timetable for U.S. troops to step back from combat.

While Obama conceded that we had “probably not ... achieved everything that some might have imagined us achieving in the best of scenarios,” he nevertheless tried to put a smiley face on the war effort. “Did we achieve our central goal? And have we been able, I think, to shape a strong relationship with a responsible Afghan government that is willing to cooperate with us to make sure that it is not a launching pad for future attacks against the United States? We have achieved that goal. We are in the process of achieving that goal.”

There is actually an important difference between the last two sentences. Which is it: Have we achieved the goal or are we in the process? If the latter, then that would argue for a continued U.S. commitment to Afghanistan; if the former, then it suggests our mission is complete.

The reality is that, though the U.S. is arguably making progress, we are a long way from our ultimate objective defined in the U.S.-Afghan security partnership agreement signed by Obama and Karzai in May: “sustainable self-reliance in security, governance, economic and social development.”

Yes, there has been substantial success in routing the Taliban out of its strongholds in Helmand and Kandahar provinces, as I have seen for myself on repeated trips to southern Afghanistan. After years of increased violence, enemy-initiated attacks fell 7 percent from January to November 2012 compared with the same period a year earlier. And as Obama said, the Afghan government is more or less cooperating with us, despite considerable friction over the handling of detainees, government corruption and other difficult issues.

But recent security gains remain incomplete. Commanders have never had the resources to launch a “clear and hold” campaign in the east as they did in the south. As a result, Haqqani sanctuaries remain intact an hour’s drive from Kabul.

And even maintaining the incomplete and tenuous gains of the last few years will be impossible unless Afghanistan continues to receive substantial U.S. assistance. The Defense Department’s Report on Progress Toward Security and Stability in Afghanistan concedes that only one of 23 Afghan army brigades is able to operate on its own. The Afghan forces, though fighting hard and taking considerable casualties, still need American “enablers” such as artillery, air support, medevac, logistics and intelligence. Afghanistan will not even have a functioning air force until 2017 at the earliest.

Delivering all that support, and maintaining a separate special operations capacity to hit top-level terrorist targets, will require a substantial presence of American troops. Afghanistan is a big country. Personnel based in Kabul cannot effectively assist Afghan units in Kandahar or Khost or hit terrorist targets there. There must be at least a handful of bases outside the capital area, and each one will need to be defended and supplied. Quick-reaction forces and medical facilities must be on call in the event of trouble.

How substantial a presence?

Retired Lt. Gen. Jim Dubik, a former commander of the training mission in Iraq, estimates in a recent report for the Institute for the Study of War that 23,000 to 28,000 troops would be needed. Retired Lt. Gen. David Barno, a former commander in Afghanistan, estimated in a December 2010 report for the Center for a New American Security that 25,000 to 35,000 troops would be needed. (Barno has since said that we could get by with substantially fewer, but he has given no reasons why his earlier analysis doesn’t hold.)

That is a far cry from the figures now leaking out of the Obama administration. Rumor has it that the administration would like to pull out perhaps half of the 66,000 troops this year and almost all the rest in 2014, leaving behind as few as 3,000 personnel. Or maybe none at all: Talk of a “zero option” has been getting louder from the White House.

Obama has a perfect right to decide that the costs of victory in Afghanistan are too high. But if so, he should level with us instead of insulting our intelligence by claiming that we have already won a war that shows no sign of ending any time soon.

