Nato supply trucks have resumed travel between Afghanistan and Pakistan, following a seven month blockade. The roads were reopened after the US apologised for an airstrike that killed 24 Pakistani soldiers in November. The Taliban has pledged to attack the convoys en route to Afghanistan from neighbouring Pakistan. Gunter Katz, brigadier general of the International Security Assistance Force, tells Al Jazeera that ISAF is working to strengthen security measures to counter the Taliban threats.