STRONG POINT HAJI RAHMUDDIN II, Afghanistan -- When the last U.S. soldiers to occupy this squat, lonely outpost in southern Afghanistan pulled out this week, they left the same way earlier units had arrived: ready for a fight.
They were leaving this violent patch of land outside Kandahar, the south's main city, just as Taliban fighters were filtering back in from winter havens in Pakistan. It was, as 1st Sgt. Jason Pitman, 35, bluntly put it, "no time to get stupid."
The Americans knew that they would be most vulnerable in their final hours after taking down their surveillance and early-warning systems. The Taliban knew it, too, and intelligence reports indicated that they had been working with sympathetic villagers to strike at the departing soldiers.
Two days earlier, the militants made a test run against the outpost, taking the rare step of directly engaging it in a firefight, albeit a brief one, soon after the first radio antennas came down.
On the same day President Barack Obama announced that roughly half the U.S. troops still in Afghanistan would withdraw this year, and that Afghan forces would begin taking the lead in the war, the smaller-scale departure from the Haji Rahmuddin II outpost was an uncelebrated milestone. But it pointed at a harsh reality of the process: that some withdrawals will happen under fire, in areas of the Taliban heartland where the idea of Afghan-led security remains an abstraction.
With the start of the annual fighting season just weeks away, some of the war's hardest-won gains are at risk of being lost.
In the years since the Obama administration's additional tens of thousands of U.S. soldiers and their Afghan allies pushed into the grape fields, pomegranate orchards and opium poppy fields of southern Afghanistan, some islands of relative calm have been cleared. But even though this corner of Kandahar province -- the Zhare district -- was also a focus of the troop increase, it is far from calm.
And it is not unique: Many areas in the south and east, where troop pullouts are under way, have had only tenuous security gains at best, despite years of hard-fought U.S.-led advances.
The U.S. withdrawal is picking up pace regardless, and U.S. commanders have begun to cede even the most contested ground to Afghan forces.
There are still places "the Taliban can find sanctuary, and we still believe there is an informal network or support structure in place that they can rely on," said Maj. Thomas W. Casey, executive officer of the 3rd Battalion, 41st Infantry, which operates in Zhare's eastern and central half.
So the Americans are out on patrol alongside Afghan units almost daily, and running larger operations on a regular basis. On Thursday, they demolished a hill the Taliban had used as a fighting position. Three huge explosions reduced the hill to dust and dirt. The Americans on the mission outnumbered Afghan soldiers nearly 3 to 1.
There are some things the Americans must do solo because the Afghans cannot do them, nor will they be able to anytime soon, commanders say. One example is using high-tech surveillance -- blimps, drones, cameras mounted on towers at every base -- to help spot militants before they attack, and to direct airstrikes against them. They have launched numerous such attacks in the past month alone.
The Afghans send out regular patrols on their own, and conduct a growing number of small, independent operations. Their fighting ability is getting close to where it needs to be, but the army's crucial back end -- the logistics and supply teams that get bullets, fuel, food and water to where they need to be -- is woefully unready, say U.S. and even some Afghan officers.
But with fewer U.S. troops here, Afghan forces have to fill the holes.
"There's no white space in Zhare -- white space being the area that no one owns or controls," Maj. Casey said. If an area is not occupied by U.S. or Afghan forces, "it's occupied by the Taliban. It's red space."
Unless Afghans can hold what U.S. forces give up, he said, "more space is going to turn red."