The Taliban in Pakistan said it had a hit list of who to target during the mass slaughter that took place at a school in Peshawar on Tuesday.

Tehrik-e-Taliban Pakistan, or TTP, said Thursday the attack on the Army Public School, which is run by the country's military, that killed 132 children was meant to target the sons of military officers who attend the school.

"More than 50 sons of important army officers were killed after being identified," the TPP said according to Bloomberg News. "The auditorium where students of secondary and higher secondary sections were being taught first aid was targeted."

The extremist group, which wants to dismantle Pakistan's government in favor of strict Islamic law, also said the killings were revenge for a Pakistan offensive to expel Taliban fighters from the country's North Waziristan region.

Tuesday's massacre, said to be one of the deadliest in the country's history, was organized by TTP members working from neighboring Afghanistan, a Pakistani security official told Bloomberg, citing "very credible" sources.

The same unnamed Pakistani official said they have proof the organization's leader, known only by the name Fazlullah, is operating in Afghanistan's Kunar and Nanagarhar provinces. Both provinces are near Peshawar across the border.

Leaders from Pakistan and Afghanistan expressed a "common resolve" to defeat the terrorists to prevent another tragedy like the one in Peshawar, which left about 150 people dead and over 100 wounded.

But experts are skeptical any sweeping anti-terrorism measures will be implemented in a country where thousands have already been killed by terrorism with no solution, peaceful or otherwise. The last attack of this scale was in 2007 when 140 people were killed by a suicide bomber at a political rally for the late Prime Minister Benazir Bhutto.

"The equivocal tone often used by Pakistan's politicians in talking about the Taliban has clearly been replaced by robust condemnation in the wake of the attack," Oliver Coleman, an analyst from Verisk Maplecroft, a global risk forecasting firm, told Bloomberg.

"However, the idea that this atrocity will galvanize political leaders to come up with a unified response to the Taliban should be treated with caution."