By M Ilyas Khan
BBC News, Islamabad
It has taken four months for the Pakistani army to launch an operation in the volatile tribal region of South Waziristan.
What held the army back and what can the security forces expect now?
The announcement that a ground offensive had been ordered was first made in June and troops have been gathering on the border since then.
The four-month delay enabled the militants to overcome the reverses they had suffered in the Malakand region during the summer, and to hit back at the government with added force.
Hundreds of people have been killed in scores of militant attacks during this period.
The militants also suffered setbacks. Former Taliban leader Baitullah Mehsud was killed in a suspected US drone strike in August.
His death led some security analysts to suggest that there was now no need for a full-blown operation, and that small-scale, localised action would take care of the menace.
But despite army rhetoric about why a timeframe could not be put on any South Waziristan assault, the authorities have decided that now is the time to attack the militants in their stronghold.
Plagued by delays
Doubts about the fate of the operation emerged just a week after the announcement of the operation by the governor of the North West Frontier Province when a pro-government militant leader, apparently being groomed by the army to defeat and replace militant commander Baitullah Mehsud, was assassinated.
Many civilians have already fled South Waziristan
Subsequently, during informal briefings held by the army's top brass for members of the media, the officials spelt out a range of other reasons why the Waziristan operation could not proceed in time.
The impression conveyed was that the country's civilian government had not been quick enough to rehabilitate the system of administration in other areas cleared of militants.
These officials cited the example of the operation in Swat and other areas of Malakand region.
They said that despite the success of that operation, launched in early June, the government had failed to beef up the local police force or fill the judicial vacuum.
As a result, the army was not able to free up troops for operations in other areas, the argument went.
The army there continues to be involved in combating remnants of militant groups for fear that, if it thins its presence, the gunmen may stage a comeback
In addition, the army in Malakand was weighed down by the "logistical burden" of about 8,000 arrested militants.
Officials said the army was holding these militants because police could not cope with such a number.
Furthermore, the courts and anti-terrorism laws are inadequate to carry out trials, or achieve convictions.
This loss of time delayed the South Waziristan operation right up to the winter, which is now setting in and which officials have in their briefings discounted as a suitable time an operation.
But there have been counter-arguments that call the army's declared reasons into question.
Pakistani troops still maintain a presence in Malakand
First, the terrain in the north-eastern parts of South Waziristan, which is envisaged to be the main theatre of war, is not as difficult as that in Malakand.
Thick forest cover and lots of water made nearly the entire Malakand region suitable for militants to create hideouts and to lie low there for longer periods.
But South Waziristan is an arid zone, with no forest and little water.
Second, the likely war zone in South Waziristan is sparsely populated, and most of the population has already left the area, effectively cutting the possibility of civilian casualties.
Third, the troops deployed in the South Waziristan region are more than twice the numbers that conducted the Malakand operation, even though the area of the combat zone is smaller.
Fourth, the army has had the experience of operating in Waziristan since 2002, whereas it was a complete stranger to the Malakand region.
Fifth, the winters in the Mehsud area of South Waziristan are not as harsh as in some other areas and have not prevented the army from conducting operations there in the recent past.
Given these factors, security analysts believe there may be two main reasons why the army has been putting off action against this destructive ground-zero of al-Qaeda and the Taliban in Pakistan.
Any action against the Baitullah Mehsud group in South Waziristan could draw in to the conflict militant groups based in the Wazir tribal areas of South and North Waziristan.
These groups are part of the al-Qaeda-affiliated Haqqani network, and have peace agreements with the army.
They have so far concentrated exclusively on fighting inside Afghanistan, and many analysts consider their activities central to the army's perceived security interests in South Asia.
Any hostilities with them may harm these interests, analysts say.
Another reason may well have been the US government's so-called Kerry-Lugar bill which promises $1.5bn (£0.95bn) in annual aid to Pakistan for the next five years.
The bill offers an unprecedented chance to the country's civilian government to expand its clout over the state institutions at the cost of the military, which has until now monopolised political decision-making.
Last week, the army publicly denounced the bill at a time when the government was defending it, thereby sparking a rift in the political establishment.
But the dizzying pace at which the militants have struck at targets across the country during the last couple of weeks has increased public pressure on the army to deal with its erstwhile proteges.