AFP

AFTER descending the jagged heights of South Waziristan, a remote part of Pakistan that borders Afghanistan, Wazir Khan Mehsud reached safety last week with his three small children, 40 other relations and their bundled possessions. They had come to Dera Ismail Khan, in the “settled area” of North-West Frontier Province (NWFP) that borders Pakistan's semi-autonomous tribal belt, to escape an army assault on the local Taliban. Militants of the Mehsud tribes, these fighters represent one of the most formidable of several tribally based Islamist gangs in north-west Pakistan. The army now vows to crush them.

Recent acts of terrorism confirm the need for this. On October 9th a suicide blast in Peshawar, NWFP's capital, killed 52 people. On the following two days the army's headquarters in Rawalpindi were attacked by ten militants, five of them from South Waziristan. Three were said to be Uzbeks, members of an Islamist group driven from Uzbekistan into Afghanistan and from there, after America's invasion of 2001, into South Waziristan. In a 22-hour battle, nine militants and 14 others, including a passing brigadier, were killed. It could have been worse. The militants at one stage made 22 hostages huddle round a suicide-bomber. Pakistani commandos shot him dead. Another teenage suicide-bomber killed 45 people on October 12th in NWFP's Malakand region, which the army captured from another Taliban gang in May. And on October 15th roughly 25 militants launched co-ordinated attacks on three police bases in Lahore, as a suicide-bomber drove into a police station in Kohat in the north-west.

All these attacks were probably launched from South Waziristan, long the most hostile of Pakistan's seven Federally Administered Tribal Areas. Despite at least three army offensives and peace deals with the Mehsud and other militants, the region has been a jihadist haven, more or less, since 2001. Besides the Uzbeks, al-Qaeda and a ragbag of Punjabi jihadist groups are present. And the Taliban have learned their arts. A Mehsud commander called Qari Hussain has become famous for training suicide-bombers. The army reckons that, of over 200 suicide blasts in Pakistan in the past two years, 80% were launched from South Waziristan.

Since ending its Malakand operation, which it considers a turning-point in a previously undistinguished seven-year campaign, the army has deployed 28,000 troops to blockade the Mehsud's fief, which has also been bombed. Over 100,000 people, a third of the population, have fled into NWFP. Most, given the hospitable way of Pushtuns, have found shelter with relations. They have no alternative. Unlike the offensive in Malakand, in which over 200,000 of the 2m displaced people were allowed sanctuary in refugee camps, this operation provides no shelter for Mehsud fugitives.

For security reasons, the United Nations, which lost five staff when a suicide-bomber attacked an office of the World Food Programme in Islamabad on October 5th, is also absent. And the army has often prevented local charities from dispensing food aid to the Mehsud refugees, apparently fearing this would be funnelled to the Taliban. In dusty Dera Ismail Khan, where most of the displaced have been registered, no food has been distributed for a month. Arriving footsore and broke in Dera Ismail Khan, Wazir Mehsud was dismayed to discover so little to eat, and that his house back in South Waziristan had been flattened in an air raid.

The army is now planning a ground attack on the Mehsud militants. The terrain is forbidding and, with the winter snows expected next month, so is the weather. The Mehsud Taliban also seem to be in better shape than the army had hoped.

Their leader, Baitullah Mehsud, was killed in August by an American drone. He was also the supreme commander of Tehrik-e-Taliban Pakistan, an alliance of 13 Pushtun Taliban groups of which he had been a founder. On his death a leadership battle ensued, motivated, the army claims, by his lieutenants' desire to lay hands on a vast fortune that their dead “emir” had accrued by extortion and foreign donations. A 28-year-old militant, Hakimullah Mehsud, allegedly al-Qaeda's favourite and a cousin of Qari Hussain, was declared his successor. But, until this month, when video footage of him was televised, he was thought by foreign and local spies to have been killed in a fight with his chief rival, Waliur Rehman. Some reports said Mr Rehman, who had been put in charge of South Waziristan, was also dead. But he was heard on a telephone intercept on October 11th exhorting a follower to pray for success in the Rawalpindi attack.

In another sign of the Taliban's resilience, the army has had limited success trying to divide them. The leader of a rival Mehsud Taliban militia, supported by the army, was killed by the genuine article in June. Having no popular support, its fighters are locked down in Dera Ismail Khan under army protection.

The army seems to have done better in buying off the Taliban belonging to other tribes. To help keep the Mehsud fighters out of NWFP, it has armed militants of the small Bhittani tribe, despised by the Mehsud. It also seems confident that it can ensure the neutrality of two powerful Taliban commanders of the Wazir tribe, Mullah Nazir, who controls most of the rest of South Waziristan, and Hafiz Gul Bahadur, in neighbouring North Waziristan.

Despite the almost permanent state of war between the Wazirs and the Mehsud, these commanders forged an alliance with Baitullah Mehsud last February. And in June, when the army began its operation in South Waziristan, it seemed they might even honour it: Mr Bahadur's men killed at least 23 soldiers in an ambush. But the army, which exacted a bloody revenge for that attack, considers this unlikely. If history means anything, it will have paid hefty bribes to Mr Nazir and Mr Bahadur, with whom it has also previously made peace deals. In recent days it has showed restraint in repelling attacks by Mehsud and Uzbek militants in North Waziristan, viewing these as an effort to draw Mr Bahadur and his men into the fight.

A longer version of this article appears in The Economist print edition.