Last week, Taleban terrorists stormed an army-run school in Peshawar, Pakistan, killing at least 132 children and committing one of the deadliest attacks against children in recent years.
The incident adds to a decade of terrorist activities which are becoming more cold-blooded and wanton than ever before and are particularly targeted at children, say historians and criminology experts.
These innocent lives, they say, are regarded by every culture as worth protecting, which makes them the prime targets of modern-era terrorists who are out to make the most impact possible with their acts of violence.
"Terrorists are looking for something of value that they can strike... targeting children is something that really hurts," said Professor Emerita of History Anna Geifman of Boston University, who is also senior researcher at the political studies department at Bar Ilan University in Israel.
"Terrorists want to show that they are willing to do anything so... we should take them seriously," added Professor Laura Dugan from the Department of Criminology and Criminal Justice at the University of Maryland.
Previously, terrorists "had their own code of how to behave", said criminal justice administration professor Gus Martin of California State University.
American terrorists, he said, would plant bombs and dial ahead so buildings could be evacuated, or Pakistani hijackers would free captives before blowing up the plane.
But that morality began to shift in the 1990s, especially with the appearance of groups like Al-Qaeda; and on Sept 11, "a new era had dawned", said Prof Martin.
"Now the moral compass has completely changed - many of these groups have no hesitation in killing as many as possible."
Prof Geifman, who has written a book on terrorism called Death Orders, added that after the 9/11 attacks, terrorists had to look for the next "sensational and impressive" act of violence, and that was when they turned to children.
One of the most notorious acts of terrorism targeted at children was the school attack and hostage-taking in Beslan, Russia in 2004.
Rebels took over the school for three days and held 1,200 students, teachers and parents hostage in the school gym. They turned it into a death camp, denying children food and water.
Many died when a bomb was detonated in the building, while others were shot by the rebels as they tried to escape.
According to reports, more than 700 were wounded and more than 300 died - 186 of them children.
Prof Dugan said attacks on educational institutions "started increasing dramatically" that year. And in the years after, it "becomes clear that schools that are targeted have young children attending them".
The proliferation of child victims could also have to do with terrorist groups copying each other, said experts. Prof Dugan said such trends have emerged before: "Suicide attacks have spread across groups since the early 1980s... another example is airline hijacking in the late 1960s and early 1970s."
In the case of Boko Haram, the terrorist group that kidnapped nearly 300 girls in Nigeria in April - and another batch of at least 185 a week ago - the attacks are a statement against Western education and the education of women. It believes that women should be at home raising children and looking after their husbands instead of getting educated.
Some of these women are "kidnapped and sold into slavery", said Prof Martin.
Another explanation for targeting children is to make a "counterculture" statement, said Prof Geifman.
"Whatever is precious in the other culture, they will try to negate and destroy."