Although Tuesday’s attack sparked widespread condemnation, current and former U.S. officials expressed cynicism that the bloodshed would cause Pakistan's military to change its view of militants.

Munter and other officials said the United States has been unable to break a powerful, army-backed narrative in Pakistan that militant attacks are the result of America’s war on terror. Foreign powers, not Pakistan, are responsible for growing militancy in Pakistan, according to the narrative. And Pakistan is not responsible for the problem and unable to stop it.

That narrative played out immediately when Pakistan’s army chief, General Raheel Sharif, flew to Afghanistan within 24 hours of the attack to meet Afghan leaders. They said they had information that the school attack was directed by militants hiding inside Afghanistan. "We are hoping that we will see strong action from the Afghan side in the coming days," said Pakistani army spokesman Major General Asim Saleem Bajwa.

One senior American official said he hoped the trip was not "communications Kabuki" designed to divert blame for the failure to stop the attack away from the Pakistani army. Analysts said the army is failing to own up to its decades-long history of training, funding, and sheltering some militant groups and using them as proxies to counter archrival India in Afghanistan and Kashmir.

Since 2001, a parade of American officials—from presidents to CIA directors—have repeatedly warned Pakistan's generals that they will lose control of their militant proxies and eventually be attacked by them. Pakistani military officials have denied sheltering militants.

But some current and former U.S. officials said the sheer brutality of this week's attack would intensify demands from Pakistan's public for the army to confront militancy. James Dobbins, who served as the Obama administration’s special representative to Afghanistan and Pakistan from 2013 to 2014, said there was also growing pressure from Pakistan’s longtime ally China. “I think they are pressing Pakistan to take this threat more seriously,” he said.

Munter, the former ambassador, argued that the problem reflects a more fundamental question of whether militants have become so entrenched that the Pakistani army cannot defeat them. The senior administration official was more optimistic, contending that even before the school attack, the Pakistani public was raising pressure on the army to act. The ongoing military operation in North Waziristan that militants said prompted the school attack was evidence of change.

"There has been a growing sense in Pakistan that this is an issue that they need to deal with,” said the senior official, who asked not to be identified by name. But Shamila Chaudhary, who served as senior director for Pakistan and Afghanistan on the National Security Council from 2010 to 2011, warned that as U.S. attention has shifted elsewhere, the steady deterioration of Pakistan’s institutions, security forces, and economy has continued.