Islamabad - Salahuddin Khan had just finished paying a call of nature behind a bush when military jets roared over his village in Pakistan's mountainous South Waziristan tribal district bordering Afghanistan. As he froze in fear a shell hit with a bang where his home was situated. Khan hurried back, murmuring prayers for the safety of his family. To his immense relief, one of the outer walls of his house had collapsed - but everyone was safe.
Around fifty metres away, however, three homes, including that of a local Taliban commander, were flattened and the people buried under the debris were screaming for help.
As dozens of Islamist insurgents dug the rubble with spades and even bare hands, Khan left his house in the darkness with his wife, three daughters and four sons.
Khan, 30, and his family travelled on bumpy roads for next two days to reach Tank, the first town outside the tribal region on Saturday when Pakistan announced it had started a long-anticipated assault on the sanctuaries of Taliban and al-Qaeda in South Waziristan.
The offensive came after a four month campaign to soften up Taliban targets with selected air strikes.
"Everyone is leaving South Waziristan. There is going to be big bloodshed because Taliban are ready to fight in the villages, mountains and forests," Khan said as he stood in a long queue to register himself at a refugee camp.
Some 100,000 inhabitants have already fled the conflict zone and the same number agaub were on the move as dozens of tanks inched towards Taliban hideouts for what Pakistani officials have described as "the mother of all battles."
Pakistan forces have been encouraged by a successful operation in Swat, a scenic valley in North Western Frontier Province where they regained control after killing around 2,200 Taliban fighters - following a mass exodus of nearly two million people.
The situation in South Waziristan is different and far more complicated than Swat, where Taliban were much less experienced in guerrilla warfare and fewer in numbers.
Between 10,000 and 15,000 hardcore Taliban fighters are believed to be operating in the area, hoping to ambush some of the 30,000 soldiers deployed for the operation.
South Waziristan is an area of around 6,620 square kilometres consisting of plain fields, jagged mountains and dense forests.
The Taliban fighters have dug new tunnels, camouflaged mortar guns on the hilltops and planted roadside bombs along the routes anticipated to be used by the troops, according to one Pakistani intelligence official.
The official - who spoke on condition of anonymity - said tough resistance was expected from around 1500 Uzbek and al-Qaeda linked Arab fighters who have a kill or die philosophy.
The military offensive is expected to please the United States, who have been pressing Pakistan for many months for an all-out attack on the Taliban, who have been frustrating international troops in Afghanistan with deadly cross-border raids.
But Pakistan is mainly focussed on the domestic threat from Tehrik-e-Taliban Pakistan - an umbrella organization of around a dozen terrorist outfits - responsible for scores of suicide attacks across Pakistan over the last two years.
Hakimullah Mehsud took up the reins of the group after his clansman and former chief Baitullah Mehsud died in a US drone attack on August 5.
Under Hakimullah, the militants have launched a series of sophisticated and brazen attacks on security installations in recent days.
These include last weekend's hostage drama on the country's military headquarters in the garrison town of Rawalpindi, adjacent to capital Islamabad.
Twenty-three people, including 10 soldiers, died in the incursion that caused huge embarrassment for the Pakistan's Army - the world's sixth largest in numbers.
Hakimullah and his associates are classified as "bad Taliban" by the country's leadership, as opposed to the "good"Taliban who focus only on resistance against the "foreign invaders" in Afghanistan.
Commanders like Maulvi Nazir in South Waziristan, Hafiz Gul Bahadur in North Waziristan and Afghan commander Sirajuddin Haqqani, whose network has presence across Pakistan's tribal belt and is considered as Pakistani Taliban's supreme leader, are among them.
Altogether, they are estimated to lead between 30,000 and 40,000 fighters in Waziristan area.
"Much depends on what we call 'good Taliban'," said Pakistan's former ambassador to Afghanistan and currently a security analyst, Rustam Shah Mohmand. "If they decide to stay neutral, the operation in South Waziristan can be successful."
In order to keep "good Taliban" neutral, the Pakistani government will have to hope for a speedy victory.
"They (the army) might try to do what American did in Afghanistan in 2001, to destroy the strongholds of militants, disperse them and announce their victory," said defence analyst Dr Ayesha Siddiqa.
"But that would not eliminate Taliban threat from Pakistan. That threat would remain there in form of 'good Taliban'," she added.
Even if the good Taliban stay quiet, the supporters of Mehsud group could prolong the conflict by carrying out attacks in urban centres as they have done in the recent days.
"Taliban will put up strong resistance as army will try to destroy their control. Taliban may also intensify their terror campaign in the mainland to divert attention and cause panic among the common people," warned Siddiqa.
