In spite of its cruelty, though, analysts say this latest assault is a desperate act by an organization that is outgunned, riven by in-fighting and unable to muster popular support.
"The Pakistani Taliban has never shown that it can be a mass movement," says Tony Cordesman, a former security adviser in the U.S. government, now with the Centre for Strategic and International Studies in Washington, D.C.
And Tuesday's attack is unlikely to further its cause, he says. "It's really hard to see how this is going to intimidate anyone, rather than making them incredibly angry."
In justifying the attack on the military-run school in Peshawar in northwestern Pakistan , Jihad Yar Wazir, a commander with the TTP (Tehrik-i-Taliban), told the Daily Beast that parents of the children at the army school "are behind the massive killing of our kids and indiscriminate bombing in North and South Waziristan" and that targeting them at a school "is perfect revenge."
He added that his organization is "is ready for a long, long war against the U.S. puppet state of Pakistan."
The Pakistani Taliban is a branch of the Sunni militant group that emerged in the early 1990s from the rubble of the Soviet invasion of Afghanistan.
Made up largely of members of Pashtun tribes in eastern Afghanistan and western Pakistan, the hardline Islamist group eventually took over the Afghan state in the mid-90s, governing according to sharia law.
After being ousted by the U.S.-led military coalition for harboring al-Qaeda leader Osama bin Laden in the early 2000s, the Taliban became an insurgency group.
Militants in both Afghanistan and Pakistan still carry out public attacks in the name of the Taliban, but the group has actually split into numerous factions, says Cordesman.
They're ultimately united in wanting to roll back U.S. influence in the region. But they each have their own ideas about the necessity of violence in achieving those aims, he says.
For example, during the recent elections in Afghanistan, the Taliban branch there mused openly about peace talks and a power-sharing agreement with a new government.
In May, a group previously allied with the TTP announced a "complete separation from the current organization that has lost its way," and added that it was renouncing violence.
Cordesman says that the Taliban's political ambition is "one of the areas where they are deeply divided."
"Again and again, the question is, are they attempting to get majority support or are they attempting to be an extreme movement attracting extremists and people who believe in their cause to support them with money?" he says.
Polls and votes continue to show that the Taliban does not represent the mainstream of Pakistani thinking. The average Pakistani citizen is more tolerant than the rigid ideologues of the Taliban, and "not as interested in extremism," he says.
"Even if you agree with the Taliban religiously, what are they offering by way of a future, of development, of education? Not much."
This latest attack can be seen as a response to a tightening of the Pakistani military's actions against the Taliban in the Waziristan region, says Jonah Blank, a senior political scientist at the Rand Corporation.
The Pashtun areas of Pakistan have never really been administered by the state, so ever since British colonial times, "the way the central government dealt with these Pashtun communities was to say, 'You do your thing, we'll do ours, you don't bother us, we won't bother you,'" says Blank.
"That was the case for well over a hundred years. The British basically invented it, and the Pakistani state continued doing it right up until the present time."
But because of increasing U.S. pressure on the Pakistani military to stamp out extremism, as well as power struggles within the Pakistani Taliban over their aims, the TTP faction has become less interested in maintaining this relative peace, Blank says.
The TTP "has gradually become more and more antagonistic towards the Pakistani government and more unwilling to abide by this more traditional live-and-let-live arrangement," he says.
A new narrative
As far as a political ideology is concerned, the Pakistani Taliban is "a very, very fringe group," says Omar Hamid, head of Asia Pacific country risk at the U.S.-run global intelligence firm IHS.
But, for a long time the Pakistani government was unable to "create an anti-Taliban narrative" that would discredit them in the eyes of the Pakistani public, he says.
That changed with an attack the group coordinated at Karachi airport in June with an Islamic group from Uzbekistan, an attack that killed 36 people (including the 10 attackers).
The airport assault created a wave of public support for a military offensive in Taliban-held areas of northwestern Pakistan, which began a few days later. Led by the Pakistani military, the months-long foray included American drone strikes and was endorsed by Islamic scholars in Pakistan.
"Any sort of ambivalence about whether there should be peace talks or should there not be peace talks seems to have vanished over the past five to six months," says Hamid.
"And I think after this [latest] attack, you will only see a further strengthening of that" resolve on the part of Pakistan authorities.
ALSO ON HUFFPOST: