Militants struck back, hitting the military’s headquarters in Rawalpindi, a mosque where military families prayed, and the offices of Pakistan’s intelligence agencies in three cities. The number of Pakistani civilians killed last year in Taliban attacks exceeded civilian deaths even in Afghanistan, helping shift public opinion against the militants.

“I think it has become very dramatic that these people are out after them,” the diplomat said.

The fighting — coupled with intense American drone strikes in the western tribal region — has splintered the militant groups, which are now a poisonous mix of Pashtun tribesmen, Arabs, Uzbeks and ethnic Punjabis, known for their brutality against Shiites and their close links to Al Qaeda.

The fracturing is so profound that one Pakistani government official in the tribal region said that the Pakistani Taliban now consisted of several parts operating independently, and that the groups “do not necessarily take orders from Hakimullah Mehsud.” But the widening military campaign has also given them common cause. Operations by the militants have become more fluid. “All these groups are helping each other out and selling their services to the highest bidder,” the diplomat said.

Pakistani officials recognize that the evolving nature of the militants has made them more dangerous — and made the necessity of going after them in North Waziristan increasingly unavoidable. “Their nexus with the Punjabi Taliban have given them greater reach,” a Pakistani law enforcement official said.

But even as there is a growing consensus that North Waziristan is now the source of the problem, there is a continuing debate in the military over when and how to tackle it. Publicly the Pakistani military is saying that it is already fighting on several fronts, and that it does not have the resources to push into North Waziristan for at least several months. Western officials say they believe that the Pakistani military is doing as much as it can under the circumstances.

There is also an understanding that opening a new front in North Waziristan — with its tangle of tribes, Qaeda militants, antistate groups and Haqqani supporters, thought to be in the thousands — will be a formidable task. “To go after Haqqani, it takes a very sizable military operation,” the diplomat said.

But some officials say an operation could come sooner, not least because officers on the ground are calling for it. More frequent attacks emanating from North Waziristan “are likely to lead to a reaction sooner rather than later as field commanders feel the pressure to protect their troops,” said Shuja Nawaz, director of the South Asia program at the Atlantic Council in Washington.