In Afghanistan’s Kandahar province, following a three-hour, bone-jarring drive from Pakistan, the flag of the Hezb-i-Islami guerilla force suddenly appeared in our truck’s headlights.

From behind a boulder stepped a caped figure toting an AK-47. "Dresh!" (Halt!) he bellowed. There was a muttered Pushtu conversation.

"He wants to know the name of the night," my interpreter Sayeed nervously informed me. "If we don’t know the name of the night, he is opening fire."

Fortunately, from somewhere in our truckload of holy warriors this password was extracted: "Islam phirose bad!" (Islam will triumph!) After warm chorusings of Salaam aleikum (peace be with you), we were shown our tent for the night.

The deaths of five British soldiers allegedly murdered by an Afghan policeman in Helmand, Kandahar’s neighbouring province, last Tuesday and a massacre at Fort Hood, Texas, two days later by a disaffected Muslim US Army major brought back a memory of the Soviet Afghan War and the cross-border sortie I made in 1980.

One reason for my being behind Soviet lines was one Commander Zafarruddin, who had led a spectacularly treacherous defection from the Afghan army in June of the previous year. In the wake of the news from Helmand and Texas, I’ve been asking myself whether my conversations with Zafarruddin can help explain why these events might have happened.

Prudently dressed in the Pashtun’s turban, long-tailed shirt and voluminous trousers, I had gone behind Soviet lines partly in hope of hearing at first hand the 24-year-old former regular officer’s account of his mutiny.

In 1978, when a Moscow-sponsored military coup installed a communist government in Kabul, Commander Zafarruddin (a nom de guerre) had been a second lieutenant in the Afghan Army’s 63rd Mountain Brigade in Kandahar.

As the coup leaders introduced pro-Soviet policies, anti-Kabul guerilla forces began appearing in the brigade’s area. Most active was the Hezb-i-Islami-Gulbuddin (HiG). This faction of the Hezb-i-Islami (literally, Islamic Party) had been founded by a 30-year-old engineering undergraduate named Gulbuddin Hekmatyar.

The 63rd Mountain Brigade received orders to prepare for battle with the HiG. Zafarruddin and his comrades were being forced to confront a step that they had been dreading - choosing between Kabul and a Muslim group.

Pretending sympathy for the impending battle with the HiG, Zafarruddin invited to dinner 22 officers whom he knew favoured the ruling pro-Soviet People’s Democratic Party (PDP). As the meal ended, he walked to the door, turned and emptied his pistol into the diners. At this signal, nine co-conspirators tossed grenades among the pro-PDP officers, then used AK-47s to finish off survivors.

About 1,500 63rd Mountain Brigade soldiers then followed Zafarruddin to a rendezvous with the HiG. They joined 12 guerilla bands that within months claimed control of 85 per cent of five provinces.

In the latest phase of what is now a 31-year-old war, these five - Kandahar, Zabul, Ghazni, Uruzgan and Helmand - are still the scene of the heaviest fighting. Since 2001, 696 of the coalition’s 1,506 fatalities, including this week’s five British casualties, have occurred here.

Perhaps the Russians can help us draw some lessons. In the 1990s, the Russian General Staff commissioned a detailed analysis of what had gone wrong in the Soviet occupation.

The Russian analysts took special note of the problems they had with indigenous forces. Like the current coalition, the Soviet war planners were depending on loyal Afghan soldiers and police for their exit plan. The analysis quoted early estimates that a 650,000-man force would be needed to hold Afghanistan, with most of these being local security units.

Unfortunately for Moscow, the maximum strength of Afghan armed forces was never raised higher than about 150,000. Even at this level, "the combat sub-units were 25 to 45 per cent below strength".

The main reason for weakness: "Not only conscription shortfall, but also massive desertions. Every month, an average of 1,500 to 2,000 deserted."

The Russian military analysts attached a wry parenthesis to their evaluation of the locals. The Afghans, they said, had "a complete lack of understanding of the goals and missions of armed conflict (or perhaps they understood the goals of a foreign occupation quite well)".

It is hard to tell the full extent of the coalition’s difficulties but it seems clear that trainers are having to contend with similar morale-sapping problems. At one stage, the desertion rate was reportedly as high as 40 per cent, as boot camps pushed several thousand newly trained troops into battle against the Taleban.

Last August, however, United States officials claimed that partly as a result of an increase in soldiers’ wages - US$210 and more per month for officers; US$120 for other ranks - desertions had fallen below 5 per cent. But a more recent report in The New York Times said that one of every four or five men in the Afghan security forces quits each year. Desertion might not be the only reason for departures but this figure does imply a morale problem.

President Barack Obama has rightly warned against jumping to conclusions about the Fort Hood massacre till all the facts are known. It seems likely to me, however, that the strains on the consciences of many Muslim soldiers may not be very different now from what they were in 1980.

I had asked Zafarruddin why he had chosen to fight for the HiG guerillas rather than the government.