Despite fierce fighting in Afghanistan's southern Helmand province, the U.S. military says the Taliban is failing to take and hold any significant territory in recent months.

"What we see is the Taliban are not able to hold any specific terrain. And most important is, they are not able to hold any of the population centers," Army Brig. Gen Charles Cleveland, a spokesman for Operation Resolute Support, told reporters at the Pentagon Thursday.

The U.S. recently dispatched 100 troops to support Afghan security forces struggling to beat back Taliban fighters trying to capture Lashkar Gah, the capital of Helmand province.

One of those troops, Staff Sgt. Matthew Thompson, was killed this week when an improvised explosive device detonated near his foot patrol.

But while Taliban fighters have made gains across Helmand in the past year, taking over some buildings and checkpoints, Cleveland says most of those gains have been the temporary.

"When we look at what the Taliban has accomplished, by and large they have been very local successes, and they've been temporary because in most instances, the ANDSF [Afghan National Defense and Security Force] has been able to move back out, reclaim the area, and then finally protect their population centers."

Cleveland described the typical Taliban offensive as comprising a small number of fighters who target a single objective, briefly overrun it and then are driven off.

"It's literally 15 to 20 Taliban. They will assault a checkpoint, or in some cases a district center. The ANDSF at the location, usually smaller, will withdraw. They will go back to a safer location. The Taliban will loot that place. And then the ANDSF will come back and move them out."

Cleveland said Afghan troops are becoming more capable, and now conduct 80 percent of their missions without any help from the NATO assistance forces. In about 10 percent of missions, he said, NATO helps with planning, overhead surveillance and intelligence. And about 10 percent of the time, NATO troops including U.S. forces accompany the Afghan forces, but do not go as far as the objective.

He said that while the U.S. has used expanded authorities from President Obama to assist Afghan ground operations, the Afghans themselves are conducting a significant number of airstrikes with the fledgling air force of eight A-29 planes, and 28 MD 530 attack helicopters.

Cleveland attributed the uptick in fighting over the past month, specifically in Helmand, to the Taliban's push to retake territory in what has traditionally been their stronghold.

"Helmand has always been the Taliban's main effort. It is their prime focus. It is where they invest the most energy. They started off this fighting season," Cleveland said. "What they stated is, they actually wanted to go out and hold and seize terrain so that they could start developing a sanctuary overall in Helmand."

So far, he said, the Taliban has been largely unsuccessful, and for the Afghan government forces the key is to remain on the offensive.

"We think that they are still generally on track with their offensive campaign plan," Cleveland said. "We still believe that they are generally on a positive trajectory."