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 Islamic extremists.

US airstrikes in Pakistan, launched from unmanned drones, are now averaging three a week, triple the number last year. “We're 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.  

Last week America launched its first multiple drone attack, according to Pakistani security officials. Eighteen missiles were fired from eight unmanned aircraft in Dattakhel village, killing 16 people.

The discovery of the dead US soldiers revealed that America’s shadowy war in Pakistan not only involves drones but also small cadres of special operations soldiers.

Pakistan’s 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. “I’m 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 re-opening of the school. It had been rebuilt with US aid after being bombed by the Taliban last year.

Three schoolgirls, two villagers and a Pakistani soldier were also killed in the attack, for which the Pakistani Taliban claimed responsibility. More than 100 were wounded, mostly schoolgirls.

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 told the Long War Journal.

One of those killed was Sergeant Matthew Sluss-Tiller, 35, the father of a three-year-old daughter. His mother, Jane Blankenship, 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 ISI, the Pakistani intelligence service that has close links to the Taliban.

The Americans insist the drone attacks have been a success, picking off the second and third tier of Al-Qaeda’s leadership. In August they killed Baitullah Mehsud, leader of the Pakistani Taliban. They recently claimed to have killed his successor, Hakimullah Mehsud, but Pakistan’s foreign minister said this had not been confirmed.

To the irritation of Washington, Islamabad has kept up a pretence that drone attacks are carried out without its approval, even though the aircraft are based in Pakistan.

Among the Pakistani public, there has been outcry at the attacks. Surveys constantly show that Pakistanis consider the US a greater threat than the Taliban, despite 3,021 Pakistani deaths in terrorist attacks last year.

If the drones are controversial, the presence of US soldiers on Pakistani soil is far more so. Despite a $1.5 billion (£959m) aid programme, Robert Gates, the US defence secretary, 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 Pakistan’s National Defence University.

THEY sang her praises with a country music twang in Nashville yesterday, but not even the sugary lyrics of a specially written Sarah Palin song — Change You Won’t Regret — could hide the tensions between the former Alaska governor and the dyspeptic conservative rabble-rousers collectively known as Tea Party Nation.

As the keynote speaker at the first national convention of the right-wing grassroots activists shaking up Republican politics, Palin was assured of an international spotlight last night as she paid tribute to the “everyday Americans” and “likeminded folks” who have turned anger and frustration at government policies into a 21stcentury revival of the Boston tea party revolt of 1773.

Palin’s paid appearance at a showcase for right-wing rebellion spurred fresh controversy about her political intentions and her relations with a Republican party establishment which is desperate not to derail its chances of ousting President Barack Obama after only one term.

Explaining her enthusiasm for the Tea Party activists last week, Palin praised their “patriotic indignation” and “commonsense conservative policies and values”. She also pledged to attend further rallies in Nevada next month and in Boston in April.

Yet even as she was expressing solidarity with activists fighting against an “out-of-touch political establishment”, it emerged that she had agreed to campaign in Arizona next month for Senator John McCain, her former presidential running mate on the 2008 Republican ticket. McCain is facing a dangerous Senate re-election challenge from the former congressman JD Hayworth, a conservative darling of the Tea Party movement.

After months of acrimony between the McCain and Palin camps over who was more to blame for their defeat by Obama, Palin has evidently decided that the hatchet should be buried — and not in McCain’s back.

Yet her decision to endorse a notoriously moderate Republican stalwart over a Tea Party favourite drew gasps of dismay and a flood of bewildered complaints to Palin’s Facebook page, which has almost 1.3m readers. “I’m extremely disappointed that you would campaign for John McCain,” wrote Patricia Brown, one of her Facebook fans. “He is not a conservative. It makes me wonder if you really believe what you say.”

The Texan tea set have also been stunned by Palin’s support for Governor Rick Perry, who is running for re-election this year. Perry is being challenged by Debra Medina, a former nurse and businesswoman and an early Tea Party campaigner.

“I can’t believe you are backing Perry,” said Christi Cameron, a Medina supporter. “Something is wrong.”

The fuss underlined both the fragile state of the fledgling Tea Party movement, which remains riven with policy disagreements over how its revolt should be managed, and the contradictory pressures of Palin’s widely expected presidential ambitions.

Is she buttering up the party because she intends to run for the White House as a Republican? Or will the Tea Party provide a launchpad for an independent bid? For all its chaotic quarrelling and reckless rhetoric — one speaker warned Americans they would be “boiled to death in the cauldron of the nanny state” — a convention organiser insisted that “people of quality and maturity” were emerging to lead it.

For Republican grandees scenting a comeback after the fiasco of Obama’s imploding healthcare reforms, Palin and her teatime antics represent either an opportunity or a threat, and few have decided which it is.

Even as the Tea Party was drawing up plans for a formal committee that will raise funds and direct support to conservative candidates, senior Republican officials were announcing a scheme of their own to create a new right-wing think tank that will help design the party’s future policies.

The soon-to-be-launched American Action Network includes party heavyweights such as Jeb Bush, brother of George W and a former Florida governor; Haley Barbour, the governor of Mississippi; and the former senator Norm Coleman from Minnesota.

Republican officials recognise that the enthusiasm and commitment of the Tea Party activists could prove a beneficial factor in future elections. Yet many also worry that the Tea Party image of belligerent extremism may alienate middle-of-the-road voters who might be regretting their support for Obama last year.

From the “moose-shootin’ mama” from Alaska — also described in song as “the shining light on the right that the left just doesn’t get” — there was only polite evasion last week as Palin kept the world guessing about her political intentions. The nearest she came to a hint was: “It’s important to keep faith with people who put a little bit of their faith in you.”