PESHAWAR (Reuters) - More than a month has elapsed since Pakistan announced plans for an offensive on the Taliban stronghold in Waziristan, but security analysts doubt whether an all-out assault is as imminent as many people think. Code-named Rah-e-Nejat, or Path to Salvation, optimists hope the operation will demonstrate Pakistans determination to push back the spread of militancy across the northwest and beyond by eliminating Pakistans Public Enemy Number One: Baitullah Mehsud. The head of the Pakistani Taliban and Al-Qaeda ally is holed up in his tribal lands in South Waziristan with an estimated 20,000 to 30,000 fighters. Mehsud country is a maze of serrated ridges, dried out river beds and gullies ideal for guerrilla warfare. The armys gone in before with limited success. A campaign in 2005 was dubbed Operation Enduring Failure by a Pakistani magazine, as the iron-fisted tactics further alienated the recalcitrant tribes, the army suffered heavy casualties and ended up signing peace deals with militants. Waziristan will be more difficult to clear than Swat, a broader alpine valley far to the east, where the army has been fighting since late April against an enemy estimated at no more than 2,000 hard core fighters after the criminal opportunists who had gathered around the Taliban quickly melted away. For now, the army has moved up some troops to more advanced positions and sought to seal off the roads, while warplanes carry out occasional strikes, and sometimes medium-range artillery pounds the militants positions over the hills. Right now, I dont see any large-scale preparations which suggest that operation is imminent, Brig (r) Mahmood Shah, a former security chief of the tribal areas, said. A serving senior security officer said any full-scale operation would have to wait. The basic strategy is to choke them off and keep pounding their positions as and when intelligence is available, he said. Still finishing the operation in Swat, where some 20,000 troops are tied up, the army does not want to be overstretched, or risk stirring up a hornets nest in the tribal belt. The government does not want to open too many fronts with the militants and that might be the reason for delay in the Waziristan operation, Rahimullah Yousufzai, a respected analyst on tribal areas said. The armys other constraints include a reluctance to take troops away from the eastern border facing India, and a compulsion to help a US campaign in the southern Afghan province of Helmand, by deploying more troops in Balochistan. A good many Mehsud families have quit their tribal lands in anticipation of worse to come. Tribesman Noor Alam Mehsud has taken his family to Dera Ismail Khan, the nearest city where the army is garrisoned. Military planes have frequently hit our lands. Thats why I fled here because if they launch an operation all roads will be blocked and I wont be able to get my family out, he said. One factor staying the armys hand could be fear that other Taliban factions in Waziristan could erupt in open revolt if there is a full-fledged military campaign against Mehsud. Though Mehsud lands are not contiguous with the Afghan border, his fighters have a corridor through the territory held by the other main tribe of the region - the Wazirs - whenever they want to go to fight Western and Afghan government forces. Unlike many of the Wazir Taliban factions that support the Afghan insurgency, the focus of Mehsuds activity has been against the Pakistani state. Mehsud is blamed for the wave of suicide attacks on politicians and security forces since 2007. His most famous victim is said to be Benazir Bhutto, the former prime minister and late wife of President Asif Ali Zardari. The authorities have been trying to drive a wedge between Mehsud and other militants. Wazir factions, led by Maulvi Nazir Wazir in South Waziristan and Hafiz Gul Bahadur in North Waziristan, have around 5,000 men apiece, according to a diplomat following military affairs, and till recently had avoided attacking Pakistani forces. But they are angry that the government has not done more to stop US drones launching missile strikes, and fear the army could come after them after Mehsud. Last month Bahadurs fighters ambushed a convoy and killed 16 soldiers, while Nazirs intentions are unclear, analysts say. Mehsud has already shown what can happen to militants who side with the government. Last month Qari Zainuddin, a militant who denounced Mehsud as an enemy of Pakistan, was shot dead just days later in Dera Ismail Khan.