The United States may be hopeful of a political deal with the Taliban as it withdraws troops from Afghanistan but dealing with the main enemy in the east is another matter entirely.
The Haqqani network, described as "thugs and gangsters" by one US commander, is the driving force of the insurgency along much of Afghanistan's eastern border with Pakistan, where some of the war's worst fighting takes place.
While it is allied with the Taliban, some experts say its links to Al-Qaeda and ruthless ambition to rule Khost, Paktia and Paktika provinces make it less likely to engage in reconciliation efforts with Kabul and the West.
Despite US President Barack Obama saying there was "reason to believe that progress can be made" in talks with the Taliban after announcing 33,000 troops would leave Afghanistan by the end of next summer, any deal with them would only be one element of a settlement.
"The Haqqanis, although nominally under the larger Taliban umbrella, are extremely autonomous and closely partnered with the likes of Al-Qaeda," said Jeffrey Dressler, a senior analyst at the Washington-based Institute for the Study of War.
"I think it would be unwise to entertain any sort of deal with Haqqani network leadership now or in the future. The best way to bring in the Haqqani senior leadership is either in handcuffs or a bodybag."
Based in the eastern province of Khost and the neighbouring Pakistani district of North Waziristan, the Haqqanis control their fiefdom through mafia-style intimidation and violence.
"The Haqqani network is the primary enemy force here," said Lieutenant Colonel Jesse Pearson, who commands US troops along the border in Khost.
"They are thugs and gangsters, not like some other insurgent groups who are motivated by radical ideology. They want power and money and they are going to fail."
The group, with 3,000 to 4,000 fighters, has been linked to a series of high-profile attacks including a suicide bombing by an Al-Qaeda double agent at a US base in Khost in 2009 which killed seven CIA operatives.
It was founded by the now-ageing Jalaluddin Haqqani, a warlord who made his name during the 1980s jihad against the Soviets in Afghanistan, when he received funding from Pakistan and the CIA.
He allegedly helped Osama bin Laden elude American capture after the US invasion of Afghanistan following the 9/11 attacks, but his ruthless son Sirajuddin now effectively runs the network.
"The network collects protection money and illegal taxes, and profits from smuggling, but it also runs legitimate trucking firms and used car dealerships," a US intelligence officer told AFP on condition of anonymity.
"This is mafia stuff and parallels to 'The Sopranos' TV show keep coming up."
The Haqqanis are seen as operationally independent from the Taliban but part of a broad coalition of groups operating under its aegis.
This could pose a problem in any substantive peace talks -- the United States says contacts with the Taliban are at a very early stage - if the Haqqanis did not agree to end their part in the insurgency.
Asked if the Haqqanis were less likely to renounce violence and ties with Al-Qaeda than some Taliban elements, an Afghan official speaking on condition of anonymity said: "We know that there will be people who will never want to reconcile and we have a strategy for that too, which is to continue to fight them."
Washington has pressured Pakistan to crack down on Haqqani havens in North Waziristan, where US military drones regularly target the network.
It accuses elements in Pakistan's Inter-Services Intelligence agency of having ties with the Haqqanis.
But analysts say there is little prospect of Pakistan opening a new front now that Obama has fired the start gun on American withdrawals.
Seth Jones, an Afghanistan expert at the US-based Rand Corporation, said the answer to ending the Haqqani threat to overall peace lies within the complex social structures of eastern Afghanistan.
"Haqqani has genuine support in the local tribal network, and the US finds that world very hard to understand," he said.
Pakistani analyst Imtiaz Gul believes the key to getting the Haqqani network involved in peace talks is reaching the elusive leader of the Taliban.
"Once Mullah Omar falls in line or agrees to talks, I think the Haqqanis would also be amenable to talking," he said.
Afghan and Pakistani officials say they do not know where Omar is.
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