As over a thousand Afghan army graduates raise both palms to their faces in prayer standing under blazing sunshine, one of the country's most experienced generals surveys them with a mixture of pride and trepidation.

Lined up on a stretch of cement next to rows of green duffel bags, the graduates are the latest addition to a force expected to secure most of the country by the end of 2014, when foreign combat forces are due to leave.

Amlaqullah Patyani, a tall moustachioed general in charge of all Afghan army training, fears a bumpy road ahead even for his most courageous recruits.

We have no clue how to operate the weapons that NATO gives us. And even if we did, will the weapons keep coming after 2014? he asked Reuters at the ceremony, raising a key question about the sustainability of expensive Western efforts to build up Afghan security forces.

One example given by recruits is the complex computer system used to operate Stryker armoured fighting vehicles that cost around $4 million (2 million pounds) each. Many new recruits assigned to master the system lack basic numeral skills and are unable to read the Latin script used inside.

But NATO is racing against the clock to train Afghanistan's police and army forces expected to reach 350,000-strong in order to take over fighting in an increasingly violent war, a project seen as crucial for the country to battle insurgents on its own.

RECORD SPENDING ON TRAINING

The United States poured in a record amount, near $12 billion between October 2010 and September 2011, to train and equip Afghanistan's security forces. Almost as much cash, some $11 billion, is planned for the year through September 2012.

But with all the money, and over 130,000 foreign troops in the country, the mission is missing hundreds of trainers.

The 1,810-strong training force says it has commitments for another 510 troops in the near future, and is also trying to recruit another 480 mentors -- suggesting around one-third of posts are currently open.

But finding the right skills has almost nothing to do with how much money there is or how many soldiers are in the country, NATO training mission officials say.

Air force trainers are especially needed, as are finding volunteers or spare personnel with the patience and other skills needed to mould raw and sometimes illiterate recruits into military professionals.

But senior U.S. military officials admit that money has not always been spent in the wisest ways.

We have received an awful lot of money from the U.S. government. We need to use it differently now, said U.S. Army Major General Peter Fuller, deputy commander for programs and resources within the NATO training mission.

Another U.S. official in Kabul, who spoke on condition of anonymity, said the mission was buying up high-tech equipment to satisfy Washington, while more basic needs were ignored.

The mismatch between skills and high-tech equipment has even prompted Afghan President Hamid Karzai to make a plea for a focus on sustainable training.

This could get problematic, said Major General Aminullah Karim, who oversees the army's education and training.

We need the training to be completely Afghan-led and a success. And there must be enough NATO mentors for this, he told Reuters at the sprawling Kabul Military Training Centre (KMTC) just outside the capital.

NATO and Afghan officials envision the 350,000 strong force as being roughly divided equally between the army and police, though analysts say the police are becoming a paramilitary force who do not protect civilians from the scourge of daily crime.

SUSTAINABLE FUNDING

Longer term, there are questions about how much the West will stump up for Afghanistan's army. The Afghan government hopes vast copper and iron ore mines will one day pay its bills, but they are in very early stages of development and will not bear fruit for years.

Afghanistan's Defence Minister Abdul Rahim Wardak said in October that a full Afghan national security force including army and police would cost about $5 billion a year.

But sources later said that Western powers are contemplating funding a security force smaller than the envisaged 350,000 men, as they grapple with shrinking government budgets at home.

AVOIDING A SOVIET REPEAT

The scenario Afghanistan's senior generals face now is not entirely new. The Soviet Union's exit strategy in its 1980s war was also to train Afghan forces.

The Americans are acutely aware of the comparison to their Cold War foe, said U.S. Army General William Caldwell as he travelled aboard a helicopter on the outskirts of Kabul.

Below he eyed the sandy Soviet-built KMTC training ground strewn with derelict and rusted troop carriers and wreckage from the war which lost the Soviet Union 15,000 soldiers. Three years after Moscow stopped fighting in 1989, its training was halted.

The Soviet Union built a great air force and army which was very well-equipped. But a few years later, it collapsed, said Caldwell, who has overseen all NATO training in Afghanistan for the past two years.

Caldwell said Moscow failed because its training never transitioned into being Afghan-led, eventually paving the way for the Taliban's rise to power in 1996.

But Russians argue that Afghanistan's internal instability and an equipment and cash vacuum were to blame, a scenario that could play out again when NATO's soldiers leave.

In 1992 we refused to keep supporting Afghanistan, and literally within a month we saw a total collapse of the Afghan army. Generals became mujahedeen, or ran away, said Yegor Engelgard, an expert on political Islam at Moscow Defence Brief, a specialist publication.

You can keep training, but how stable they will be as a force is a big question. I just don't see how this regime will be maintained if the Americans stop logistical support.

(Editing by Emma Graham-Harrison and Ed Lane)