Kim Sengupta: Disastrous strike was just one in a long list of German errors

Northern Afghanistan used to be seen as a relatively safe and stable area untouched by the insurgency in the south and east of the country. That, however, has drastically changed for the worse.

The air strikes ordered by the German forces on hijacked tankers causing massive loss of life and devastating political consequences came against the backdrop of increasingly ferocious attacks by the Taliban which have forced Nato to readjust its strategy.

Many of the roads outside the main towns in Balkh and Kunduz are no longer safe with the Taliban carrying out ambushes and operating roadblocks, even sometimes using Afghan police uniforms and police vehicles to carry out abductions.

Although the number of insurgents is low compared with places such as Helmand and Kandahar, Uzbeks and Chechens with links to al-Qa'ida are present in their ranks. They have built up a reputation for tenacity and brutality. The region has also seen attacks mounted by the fighters of Gulbuddin Hekmatyar, a former protégé of the CIA whom the Americans have subsequently attempted to kill.

Critics blame the German forces for allowing the infiltration of the north by the Taliban, accusing the 4,200-strong contingent of failing to take action to stem the flow of fighters, allowing them effectively to take over swaths of rural areas while the troops stayed in their barracks.

The Germans insist that they are now taking a more aggressive stance and recently around 300 of their soldiers took part in an operation alongside Afghan security forces in which a number of insurgents were killed and captured. But that may be too late. "If you let snakes into your house they breed, and then you can only kill so many if you lay down poison," said Rahim Nasrullah, who owns a transport business in Kunduz city. "We now know that if we go outside the main areas [towns], we have to give money to these people. Even then, there is no guarantee that they will not steal your goods or attack you; two of my men have been badly injured. We used to have security here; we don't any longer."

Mohammed Omar, the provincial governor, says the dangers are growing. "If the Taliban get Kunduz, they will control the whole of the Hindu Kush and we will see more and more al-Qa'ida people coming in from central Asia." Three months ago, his brother, a police commander, was killed in a gun battle with Islamist fighters.

The chief spokesman for Nato's International Security Assistance Force (Isaf), Brigadier General Eric Tremblay, says his men are doing everything to counter the threat. But he also admits that it is clear the Taliban are trying to open up other fronts to take the pressure off their comrades in the south and east.