Sirajuddin Haqqani does not carry a gun or wear a turban as he moves stealthily through the Waziristan wilderness along Pakistan's border with Afghanistan, hoping to avoid detection and getting hit by a US missile from a drone aircraft.
Yet, from his safe houses and mountain redoubts, the guerrilla commander has directed some of the most brazen attacks against US forces in Afghanistan, and is now seen as one of the most dangerous warlords in the Taliban insurgency.
Washington, with ever more strident accusations, thinks he is getting help from Pakistan's shadowy but powerful ISI intelligence agency.
The Haqqani network is a "veritable arm" of the ISI, and the agency was in contact with the group during last week's startling attack on the American embassy in Kabul, Admiral Mike Mullen, chairman of the US Joint Chiefs of Staff, told a US Senate committee on Thursday.
Pakistan's interior minister Rehman Malik rejected the accusations and warned against a unilateral US ground attack on the Haqqanis, believed to be based in the mountains of North Waziristan.
"The Pakistan nation will not allow the boots on our ground, never. Our government is already cooperating with the US ... but they also must respect our sovereignty," Malik said in an interview with Reuters this week.
Sirajuddin, the head of a group his father founded in the 1980s, says he'd look forward to a US ground attack.
"The United States will suffer more losses (in North Waziristan) than they suffered in Afghanistan," he told Reuters by satellite phone from an undisclosed location.
Still, he doesn't take chances, especially with drones overhead a constant worry -- 57 drone strikes have peppered the region so far this year, according the New American Foundation, a think-tank that keeps a database of such attacks.
Some 55 members of his family, including his brother, have been killed in such attacks. According to the New American database, at least a quarter of the drone attacks since 2008 have targeted the Haqqanis.
"I always avoid travelling in a motorcade of armed fighters, as it puts your life in danger," he said, adding that is also why he doesn't wear a turban, standard head-dress for all male Afghans, or carry a gun.
Yet he is far from being a desperate fugitive on the run. He acknowledges that Haqqani fighters now number around 15,000, making it probably the largest force among the Taliban warlords. He also moves easily across the border to areas of eastern Afghanistan where the Haqqanis are entrenched.
He even mediates disputes among the Taliban and takes part in their meetings in Afghanistan. "His word is enough," said Mahmood Shah, a former Pakistan intelligence official who monitored militants for years.
The forbidding terrain of Waziristan, which forms an ill-defined border with Afghanistan, is also his ally.
"There are certain houses and villages where the bathroom is in Afghanistan and the bedroom is in Pakistan and this creates some issues," Malik, the interior minister, said.
"That no-man's land there is not (in the) control of Pakistani forces or Afghan authorities or the US forces."
When the US invaded Afghanistan after the September 11 attacks, Taliban and al-Qaeda fighters fled through the arid hills into North and South Waziristan. The ISI, which backed the Taliban when the group came to power in the mid-1990s, seemed to turn a blind eye -- or even helped -- in their escape to Waziristan's badlands.
Sirajuddin said they were a shattered and dispirited group at first, in shock and awe of American power.
"Those were the harsh days of my life as all senior Mujahideen leaders were silent and were underground after the invasion of Afghanistan," said Sirajuddin, who is believed to be in his mid-30s.
"None of them were even willing to be called Taliban as the United States, through its media campaign, had created the wrong impression of its power and intelligence."
As was the case with Osama bin Laden, the group's patriarch and founder Jalaluddin Haqqani was a legendary mujahideen commander who worked with the Americans in the 1980s to oust the Soviet Union from Afghanistan.
Former US Congressman Charlie Wilson, whose relentless fund-raising for the Afghan resistance was depicted by Tom Hanks in the movie Charley's War, once called Jalaluddin "goodness personified." He even visited the White House when Ronald Reagan was president.
Pakistan's ISI was an integral part of the nexus, funnelling secret US funds -- Congress had outlawed US aid to Pakistan at the time -- to the mujahidden for weapons such as the anti-aircraft Stinger missile.
The relationship continued long after the Soviets left Afghanistan in the 1990s and was even exposed in some embarrassing links. The Cruise missiles the Clinton Administration fired at Laden's camp in Eastern Afghanistan in 1998, after attacks on US embassies in Africa, killed several militants -- and the team of ISI agents training them.
That legacy is at the heart of Washington's distrust of the ISI, and particularly its ties to the Haqqanis.
"We sometimes say: You are controlling -- you, Pasha -- you're controlling Haqqani," one US official said, referring to ISI head Lt. Gen. Ahmed Shuja Pasha. "Well, Pasha will come back and say ... 'no, we are in contact with them'. Well what does that mean?" the official continued, speaking on condition of anonymity.
Pakistan has repeatedly denied backing the Haqqani group.
When a suicide bomber on Tuesday assassinated former Afghan president Burhanuddin Rabbani, who was leading talks with the Taliban aimed at a political settlement of the war, the finger of suspicion was initially pointed at the Haqqanis.
A Haqqani commander in a call to Reuters denied that but no one else has claimed responsibility.
Sirajuddin told Reuters the group was not opposed to peace talks, but wants them to be broader based than what has been proposed to him.
"They offered us very important positions, but we rejected and told them they would not succeed in their nefarious designs. They wanted to divide us," he told Reuters in another interview last Saturday.
"We would support whatever solution our shura members suggest for the future of Afghanistan," he said referring to the Afghan Taliban leadership.
US officials say the Haqqani network has been responsible for some of the most spectacular attacks against American targets in Afghanistan over the past year or so, including the US embassy attack that killed five police and 11 civilians in addition to three suicide bombers.
Sirajuddin half-heartedly denied responsibility for that attack. "For some reasons, I would not like to claim that fighters of our group carried out the recent attack on the US embassy and NATO headquarters. Our central leadership, particularly senior members of the shura, suggested I should keep quiet in the future if the US and its allies suffer in the future."
The Haqqanis have also been blamed for a raid on Kabul's top hotel, an assassination attempt on President Hamid Karzai and a suicide bombing of the Indian embassy. They are believed to have helped an al Qaeda suicide bomber who killed seven CIA agents at a US base in eastern Afghanistan last year.
The Haqqani's power and influence in Afghanistan is now such that they are indispensable to any settlement of the decade-long Afghan conflict, America's longest war, experts say.
"If there is to be a meaningful cessation of hostilities, the Haqqanis will have to be part of the peace process," said Vahid Brown, an expert on Islamic militancy and author of a new book, Fountainhead of Jihad: the Haqqani Nexus.
For now, Sirajuddin is one of the world's most wanted men with a $5 million bounty on his head. He said he discovered that while listening to the Voice of America.
"I don't know why, but I could not sleep that night," he said in Thursday's interview. "In the morning, I tuned into a Pashto-language broadcast of the Voice of American and came to know about this.
"I have chosen the path of jihad and I know very well about the hardships and fruits of this path."
— Additional reporting by John Chalmers