Crumbling unity among militants could provide the Pakistan Army an opening to conduct a limited offensive against a particularly vicious Taliban group in a strategic tribal region,according to a senior military official. The target of such an operation in North Waziristan would be the most violent factions within Pakistani Taliban. Their leader,Hakimullah Mehsud,is believed to be increasingly isolated after executing a prominent former Pakistani official over the objections of senior militant leaders. Although Mehsud has been linked to attacks in neighboring Afghanistan,his main focus appears to be in plotting carnage elsewhere in Pakistan. And that makes him a prime target for the Army. Washington has long urged Pakistanis to launch an operation in North Waziristan,a region overrun by an assortment of militant groups including al-Qaida. Most US drone strikes in Pakistan take place in North Waziristan. Already there are more than 30,000 soldiers in North Waziristan,and some analysts say the Pakistani army could quickly redeploy to the area. The Army has 140,000 soldiers in the tribal regions that border Afghanistan The Pakistanis,however,are unlikely to target the Haqqani group,which the US considers its greatest enemy in Afghanistan. US Adm Mike Mullen,chairman of the Joint Chiefs of Staff,complained last week that Pakistan's secret service maintains links to the Haqqani network. The Haqqanis are Afghan Taliban who control parts of eastern Afghanistan and have bases in North Waziristan. If the Haqqanis and other militant groups in North Waziristan cooperate with a military assault against the Pakistani Taliban,that would give the Army more options. The fissures among the militants were laid bare in February when Mehsud released a gruesome video that confirmed the shooting death of former Pakistani spy Sultan Amir Tarar,better known as Col Imam,according to a senior Pakistan Army officer who spoke on condition of anonymity because of the sensitivity of the subject. As Pakistan's consul general in Afghanistan's Kandahar province during the Taliban's rule,Imam was the conduit for money and weapons to the religious movement. A former Pakistani intelligence officer,Imam met regularly with Afghan Taliban's reclusive leader,Mullah Mohammed Omar. Imam was known to have kept contact with leading Taliban in hiding in Pakistan since the US-led coalition ousted them from power in Afghanistan in 2001. Mehsud's group had held Imam for 10 months. The killing confounded Pakistani military officials. They had long believed the Haqqanis held sway over the myriad groups including militants from Uzbekistan,Chechnya and the Middle East operating in North Waziristan. "We always thought the Afghan Taliban had a sway over these groups,but Col. Imam's killing shows that no one is in control of anyone there," he said. "His death was a shock for us." Taliban members who spoke to the AP on condition of anonymity because they feared being arrested said Mullah Omar made a personal plea for Imam's life. Also requesting that Imam's life be spared was Sirajuddin Haqqani,a key leader of the Haqqani group. The senior military official said Mehsud defied Mullah Omar and Sirajuddin Haqqani and went ahead with the execution after the government and Army refused his demands to free several of his imprisoned men. Not only that,Mehsud boasted on a jihadi website about the killing,according to the SITE Intelligence Group. The same website carried an Urdu language condemnation of Mehsud's organisation,calling those behind the execution "beasts" and "ignoble killers," SITE said. The divisions that Imam's death revealed among the militant groups could provide an opportunity for the Army to hit hard at insurgents in the North Waziristan town of Mir Ali,where Mehsud set up bases after fleeing last year's military assault on his headquarters in neighbouring South Waziristan,according to Mahmood Shah,a retired army brigadier and former security point-man for the government in the tribal regions. Mir Ali is about 20 miles (32 kilometres) from the town of Miram Shah,where the Haqqanis are based. Tribal elders from North Waziristan,all of whom were too afraid to talk on record,fearing retribution from militants,said the landscape in their home region has undergone massive upheavals since the army operation in South Waziristan. They said Mehsud and his men were among the most troublesome of militants,largely because of their affiliation with criminal gangs.