Zabihullah Mujahed told RFE/RL's Radio Free Afghanistan today in a telephone interview from an undisclosed location that the Taliban believes its attacks against targets in the capital have been the most effective.
In the latest incident claimed by the Taliban, an apparent suicide bomber exploded a powerful bomb on board a police bus in Kabul on June 17, killing 35 people, most of them police recruits.
Afghanistan's Interior Ministry says it is increasing security on routes leading into Kabul to prevent further attacks in the city.
NATO says it will increase cooperation with Afghan security forces, but the alliance will not change its military strategy in Afghanistan.
Three Canadian soldiers serving with the NATO-led International Security Assistance Force were killed in Afghanistan's southern Kandahar Province on June 20 when a bomb blast destroyed their vehicle.