LONDON (Agencies) The discovery of three American soldiers among the dead in a suicide bombing at the opening of a girls school in the town of Dir last week reignited the fears of many Pakistanis that Washington was set on invading their country, according to a report in The Times. US President Barack Obama has banned the Bush-era term war on terror and dithered about sending extra troops to Afghanistan, but across the border in Pakistan, the US President has dramatically stepped up the covert war against extremists. US airstrikes in Pakistan, launched from unmanned drones, are now averaging three a week, triple the number last year. Were quietly seeing a geographical shift, an intelligence officer said. For the past month drones have pounded the tribal region of North Waziristan in apparent retaliation for the murder of seven CIA officers in Afghanistan by a Jordanian suicide bomber working with the Pakistani Taliban. The discovery of the dead US soldiers revealed that Americas shadowy war in Pakistan not only involves drones but also small cadres of special operations soldiers. Foreign Minister Shah Mehmood Qureshi insisted that US troops were in Pakistan only to provide counter-insurgency training for the Frontier Corps, a paramilitary force operating in the tribal areas. Other sources said there were about 200 US military inside the country. Im not sure you could just call it training, one official said. They are hardly behind the wire if they are on trips to schools in Dir. The three US soldiers, who have been described variously as special operations forces and civil affairs troops, were killed when their convoy was bombed as it travelled to the reopening of the school in Dir. It was officially reported that the device was a remote-controlled bomb. It has now emerged that a suicide bomber rammed into the vehicle carrying the Americans. This suggests the bomber had inside information. This attack was too perfect: they lay in wait for the convoy to pass and knew exactly which vehicle to hit, a US military officer said. Jane Blankenship, mother of dead Sergeant Matthew Sluss-Tiller, said her son had been in Pakistan on a civil affairs mission and had grown a beard for it. One official suggested the trainers may be used to pick up intelligence on drone targets, particularly because the CIA did not trust its counterparts from the Pakistani intelligence service. The Americans insist the drone attacks have been a success, picking off the second and third tier of Al-Qaedas leadership. In August they killed Tehrik-e-Taliban Pakistan chief Baitullah Mehsud. They recently claimed to have killed his successor, Hakimullah Mehsud, but Foreign Minister Qureshi said this had not been confirmed. If the drones are controversial, The Times said, the presence of US soldiers on Pakistani soil is far more so. Despite a $1.5 billion aid programme, US Defence Secretary Robert Gates had to fly into Pakistan two weeks ago to reassure its military leadership. Let me say definitively the US does not covet a single inch of Pakistani soil, he told Pakistans National Defence University.