The balance of power in Afghanistan shifted, perhaps permanently, with the reported assassination of the Taliban chief Mullah Akhtar Mansoor in a United States drone strike on Saturday.

Since the Afghan government announced the death of the Taliban founder Mullah Mohammed Omar last July, on the eve of what would have been historical peace talks, the Islamist movement he created has slowly but gradually been falling apart.

The revelation of Omar's death was as significant for the Taliban as that of Osama bin Laden's was to al-Qaeda militants based in Afghanistan and Pakistan. With Omar gone, the Taliban no longer had an undisputed spiritual leader whose every edict was law.

Many in the Taliban were furious that Mansoor, his deputy, had kept the demise of Omar a secret for more than two years.

Begrudgingly, most accepted his leadership for the sake of the unity of the group, but he was never embraced and lived in fear of being assassinated by rivals. Indeed, after being wounded last December at a reconciliation meeting near Quetta, the capital of western Balochistan province, he went into hiding.

A tactical alliance

Apparently, he travelled to Iran in late March where, according to Pakistani analyst Hamid Mir, he met with representatives of the government to discuss a tactical alliance against the regional franchise of the Islamic State in Iraq and the Levant (ISIL, also known as ISIS).

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He may well have spent much of his time there in the eastern Iranian city of Zabol, located close to the border with Afghanistan, where a notable Taliban community has lived since the US invasion in 2001, according to my sources in the Taliban.

His refusal to participate in peace talks echoed his need to offset allegations that he was overly sympathetic to Pakistan's position.

In the first instance, that seems a strange arrangement, considering the otherwise conflicting agendas of Iran and the Taliban, but it is hardly unusual in the context of Afghanistan, where loyalties shift like dunes.

For example, Hezb-i-Islami leader Gulbuddin Hekmatyar last week signed a peace agreement with the Afghan government, after having allied himself with ISIL last year, but was a guest of Iran for several years after the US invasion.

During the Soviet occupation, Hekmatyar was allied with Pakistan's Jamaat-e-Islami, a Wahhabi Islamist political party. After the Red Army left, he was supported by Islamabad in the 1991 conquest of Jalalabad, the capital of his native Nangarhar province, which straddles the border with northwest Pakistan's Khyber tribal area.

During the pre-Taliban period, Hekmatyar repeatedly tried to seize Kabul and is remembered by older Afghans as the only compatriot to have shelled the capital, in 1992.

That campaign brought Hekmatyar into conflict with forces commanded by Ahmad Shah Massoud, the defence minister and leader of the ethnic Tajik militia that resisted Soviet attempts to conquer the strategic Panjshir (five lions) Valley.

His most senior commanders included Abdullah Abdullah, Afghanistan's incumbent chief executive, who was instrumental in negotiating last week's deal with Hekmatyar.

That puts into perspective the assassination of Mullah Mansoor, as well as the role of the Taliban in Afghanistan's messy political dispensation.

Until he refused outright to participate in the peace talks proposed in January by the Quadrilateral Coordination Group - comprising Afghanistan, China, Pakistan and the US - Mansoor was classified as a potential partner in peace, by both the Afghan and US governments.

His death can only add to the instability in Afghanistan. His refusal to participate in peace talks echoed his need to offset allegations that he was overly sympathetic to Pakistan's position.

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The Taliban's brief seizure of the northern city of Kunduz last September and territorial gains in nearly all contested areas of Afghanistan was undertaken both to punish Kabul for undermining Mansoor's credibility and to consolidate the Taliban's factions, to prevent them from drifting into the ISIL camp.

Leadership credibility

Mansoor's successor will face the same challenge, with the marked difference that he will be incessantly pursued by US special forces and the CIA, which have more or less reassumed the lead military role in Afghanistan this year, following the abysmal performance of the Afghan National Army last year after taking over command from US-led NATO forces.

He, too, will have to establish leadership credibility by leading a successful year of fighting, but will struggle even more than Mansoor to prevent the inevitable fragmentation of the Taliban.

Senior US commanders pushing US President Barack Obama to approve an extended troop presence, up to 2020, largely in the form of military advisers who plan and supervise the execution of operations by Afghan troops, and are supported by special forces-CIA teams and their drones, which have delivered more air strikes this year than warplanes have.

The enhanced and extended US military role in Afghanistan is a mirror image of its strategy in Iraq, which seeks to strengthen weak central governments until they are strong enough to deal with their weakened jihadist nemeses and domestic political rivals.

However, even a cursory reading of Afghanistan's history shows that the country has been at war for several millennia and no externally imposed political dispensation has ever survived.

It remains a battlefield for competing vested interests, predominantly warlords with varying external sponsors.

As such, they always win, with taxpayers in sponsor nations footing the bill, while the Afghan civilian population pays an ever higher price.

Tom Hussain is a journalist and Pakistan affairs analyst based in Islamabad.

The views expressed in this article are the author's own and do not necessarily reflect Al Jazeera's editorial policy.