Six and a half years ago, when Abdul Baseer first started treating wounded Afghan soldiers in southern Afghanistan, he worked out of a small wooden hut which served as his office, pharmacy, surgery and sleeping quarters. He shared it with four other medics.

Now he has a gleaming, 100-bed military hospital that can do "everything except neurosurgery". Nearly every Afghan National Army (ANA) soldier who is wounded in southern Afghanistan comes through his hospital at the sprawling, and equally new, base of the 205th "Hero" Corps outside Kandahar City.

He says he has seen clear progress in the war, with a definite tilt against the Taliban on the battlefield – last year's intensive military operations to clear insurgent strongholds has led this year to a 50% fall in the number of patients, he says.

But ask Dr Baseer if he thinks the ANA is anywhere near ready to go it alone, without the help of American troops, and he lets out a panicked shout of "No!"

"These improvements can't be sustained without their help," he said.

As with many others, Baseer is waiting for Barack Obama's announcement about how many of the US surge troops will be withdrawn this year with some trepidation.

"My biggest worry is when transition happens we won't be able to fly patients directly from the battlefield to the hospital," he said. "We have to rely on the Americans for that."

Whatever the number Obama settles on, the US drawdown will mean a larger share of the burden will have to be taken up by the ANA.

To that end the army has been going through breakneck growth in the last 18 months, although western officials argue that the real leap in capability is yet to come as the huge influx of fresh recruits undergo more training and pick up battlefield experience.

"It is already happening," said Abdul Hameed, the Afghan general in charge of some of the country's most dangerous southern provinces. "Our soldiers used to run away from the enemy, but now they are running to capture them."

At the military training centre in Kandahar recruits line up in the baking sun for basic training.

In a couple of months 1,400 more will be ready, pushing the total number in the south above 20,000.It can be difficult, however, to ensure a steady flow of freshly minted officers arrive from Kabul.

General Hameed has to make a point of personally imploring new officers to fulfil their assignments. "They don't want to come to dangerous areas, so I go and tell them about the situation and say they can leave if they don't like it," he said. That said, out of a recent batch of 70 that were due to arrive, only 40 turned up.

And no wonder. The south remains highly dangerous, with the hospital receiving up to 10 casualties a day, said Baseer. Nearly 80% of cases are young men whose limbs have been ripped off by blasts from hidden bombs.

"Our biggest problem is the long border with Pakistan," said Hameed. "If they prepare a suicide bomber in Quetta, he will be here in 30 minutes."

Given such obstacles, some observers have declared Nato's transition plan to be mission impossible, saying the west has no choice but to seek a rapid political settlement with the insurgents.

Similar predictions were made about the fate of the regime left behind after the Russian withdrawal from Afghanistan in 1989, and yet it survived as long as financial backing continued to flow from Moscow.

The mujahideen were forced to wait three years for their final victory, which only came with the collapse of the Soviet Union and the drying up of the all important military subsidies.

At present it is estimated that the annual post-withdrawal bill for the US to sustain the Afghan security forces will be $6bn to $8bn a year – a figure that has caused alarm in Washington and which officials in charge of Nato's military mission are looking to reduce.

A factor that will make regime collapse unlikely is the fact that even after full transition has happened by the end of 2014 there will still be a significant foreign military presence.

The makeup of that force, where it will be based and what authority it will operate under is currently being negotiated between the Afghan and US governments.

But it is certain to include large number of foreign military trainers and specialists who perform tasks the Afghans will not be capable of – including Dr Baseer's all important medical evacuation helicopters.