A bloody day has come to an end in Peshawar, Pakistan, where Taliban gunmen stormed an army-run elementary school, killing at least 145 people, almost all of them children. The Pakistani Taliban has claimed responsibility for the attack on the Army Public School and Degree College but, shocking as the assault may be, even in a country that has in recent years been the site of a gruesome insurgent campaign, the massacre in Peshawar represents the culmination of a decade-long crusade by radical Islamists against educational institutions in Pakistan’s tribal areas.

Between 2009 and 2012, Pakistan experienced somewhere between 838 and 919 militant attacks on its schools, according to the Global Coalition to Prevent Education from Attack. Since then, attacks on educational institutions have only continued, and the total number of attacks has now all but certainly passed the 1,000 mark. Indeed, the actual total is likely to be significantly higher, due to the difficulty of gathering data in areas of Pakistan where militants remain active. In 2009 alone, the Human Rights Commission of Pakistan found that 505 schools were damaged or destroyed.

Tuesday’s attack comes on the heels of a summer offensive by Pakistani armed forces in the country’s tribal areas against Taliban forces and other militant groups. According to a spokesman for the Pakistani Taliban, the attack on the army-run school came in retaliation for that campaign, which human rights advocates say has resulted in extensive civilian casualties and displacement of local residents.

“We are doing this because we want them to feel the pain of how terrible it is when your loved ones are killed,” Muhammad Khorasani, a spokesman for Tehreek-e-Taliban, the Pakistani Taliban, told AFP. “We are taking this step so that their families should mourn as ours are mourning.”

That attack is only likely to exacerbate what is a crisis in Pakistani education, which has been strained by the twin pressures of sectarian politics and militant attacks, leaving the country’s economy lagging significantly behind that of neighboring India. According to a 2014 International Crisis Group (ICG) report on Pakistan’s education system, more than 9 million Pakistani children receive neither primary nor secondary education. Pakistan has the second-highest number of out-of-school children in the world, and 22 percent of Pakistani children legally mandated to be in school are not. Literacy rates are stagnant.

Pakistani militants view efforts to enroll the country’s children in school as a Western plot designed to undermine their retrograde interpretation of Islam. But prior to Tuesday, their attacks on Pakistan’s educational institutions were not nearly as brazen. According to the Global Coalition to Prevent Education from Attack, school attacks have tended to be carried out at night and typically amounted to the placement of small bombs to destroy school facilities.

Daytime attacks have included gun and mortar attacks on school facilities, in addition to brutal attacks on school buses. Perhaps the most notorious example was the October 2012 assassination attempt on Malala Yousafzai, the Nobel Peace Prize winner who was shot while aboard a school bus. Teachers have also been targeted, with at least 15 killed between 2009 and 2012. Several teachers have also been attacked with acid. Since then, attacks on teachers have continued, with three gunned down and killed in February.

This campaign has seen some success in disrupting efforts to educate Pakistan’s youth in government-run schools. In the Khyber agency of Pakistan’s Federally Administered Tribal Areas, for example, some 85 schools were destroyed since 2005, disrupting the education of some 50,000 children, and resulting in 56 percent of 6- to 16-year-olds there attending private schools or madrassas in 2013, according to the ICG. While exact figures aren’t available, it is estimated that hundreds of thousands of Pakistani children have seen their education disrupted.

The Peshawar school targeted Tuesday has some 2,500 pupils and counts both girls and boys among its student body. While the attack is being described as an act of retaliation for the summer offensive, the Pakistani Taliban has in the past tried to undermine efforts to provide girls with education. Before being ousted from the Swat Valley by the Pakistani military, the militant group banned girls there from attending school. Of 1,600 schools there, some 400 have been destroyed, and 70 percent of those destroyed were girls schools, according to an ICG report on combating militancy in Pakistan from last year.

Many of the destroyed schools remain to be rebuilt, the report notes.