Suicide bombing is a devastating blow for Karzai
Warnings have been coming for months, publicly from independent commentators, privately by concerned officials and military commanders: the insurgent threat is spreading north to what has been the relatively calm part of Afghanistan.
But the big death toll from Tuesday's suicide attack in the northern town of Baghlan is a devastating blow to President Hamid Karzai's government and to the Nato-led forces his security relies on. More than 40 were killed, including six politicians.
It marked a departure, said Amyas Godfrey, military analyst at Britain's Royal United Services Institute.
'The stepping up of tactics in an unexpected area shows a level of insurgency and organised terror we haven't seen in Afghanistan,' he said. 'The Taleban realised that by fighting in the south they are just not winning in terms of tactics.'
Military commanders, including the British who have nearly 8,000 troops in the region, have expressed surprise at the way the Taleban have attacked their fixed positions for so long in gunfights reminiscent of conventional warfare. UK, American and Canadian troops have fought back, and won, though often at the cost of lives and the risk of serious injury, because of superior training and weapons.
But these, too, look increasingly like short-term successes as the Taleban and their supporters - al-Qaeda-inspired Uzbeks, Chechens, Arabs or Pakistanis - change their tactics, making roadside bombs or recruiting suicide bombers.
A briefing paper recently released by the UK think-tank Chatham House said the limited mandates of the International Security Assistance Force (Isaf) and the separate US-dominated force going after al-Qaeda hideouts in the mountains bordering Pakistan had led to a lack of coherence which meant they were sabotaged right from the start by 'deficiencies at the strategic level'.
'The initial military success against al-Qaeda and the Taleban could not be consolidated,' it said. 'Al-Qaeda and the Taleban were driven to the southern and eastern border provinces where they reassembled in loose networks of smaller groups.
'A security vacuum emerged in areas in which [US anti-al-Qaeda forces] had operated against enemy forces since the newly established Afghan military and police forces were slow to build up and remained too weak to secure gained territory while Isaf was not equipped to fill this security vacuum.
'Vast swathes of the country are undermanned,' said Mr Godfrey, referring to the 'light footprint' of the Nato-led forces.
It is against this background of increasing fragility that Tuesday's attack took place. It was, said Mr Godfrey, a classic al-Qaeda operation of the kind witnessed so many times in Iraq. It was well prepared against a target - Afghan MPs - which would ensure it would have a big impact and further destabilise Mr Karzai's weak government.