Pakistani  children leave Army Public School after it reopened following an attack by Taliban militants, in Peshawar, on Monday. Dressed in green blazers, young girls and boys walked into the school with their parents amid tight security. Pakistan military chief General Raheel Sharif attended a ceremony to mark the reopening after the December 16 attack.

AFP/Peshawar

Survivors of Pakistan's worst-ever militant attack returned on Monday to the school where Taliban gunmen massacred their classmates, with students and parents expressing a mixture of defiance and apprehension.

The December 16 attack on the Army Public School in Peshawar claimed the lives of 150 people, mostly children, and prompted a bout of national soul-searching even in a country used to high levels of violence.

Across the country, schools had remained shut for an extended winter break as authorities strengthened security and announced new measures including the death penalty to combat insurgents.

Most reopened on Monday along with the army school in the northwestern city.

For 16-year-old Shahrukh Khan, who was shot in both legs while pretending to play dead in his school's auditorium, going back was traumatic.

"I have lost 30 of my friends. How will I sit in the empty class, how will I look towards their empty benches?" he told AFP before the school reopened.

"My heart has been broken. All the class fellows I had have died. Now my heart does not want to attend school," he added.

At least 20 soldiers were seen at the main entrance of the Army Public School, with an airport-style security gate installed at the front.

Elevated boundary walls with steel wire fencing have been put in place in some schools around Peshawar and nationwide.

Raheel Sharif, the head of Pakistan's powerful army, made an unannounced visit with his wife, greeting and hugging students dressed in green blazers.

US Secretary of State John Kerry, who is currently in Pakistan on a surprise two-day visit, is also reportedly scheduled visit the school, according to Sartaj Aziz, the national security adviser to Prime Minister Nawaz Sharif.

'A million mothers praying'  

Parents spoke of having to sit down with their children and mentally prepare them for their return to the school, which has undergone a complete renovation to remove all traces of the bloody attack.

"He was terrified but we talked him up. We cannot keep him imprisoned between four walls and we must stand against militancy," Muhammad Zahoor said as he walked his son along the city's main Warsak Road.

"I want to go to school to see my friends. I will join the army after my schooling and will take revenge," said Muhammad Zaid, his son.

Of the 150 victims killed in Pakistan's deadliest-ever militant attack, 134 were children.

Survivors recounted Taliban gunmen moving from room to room hunting for students and teachers. Sometimes the militants toyed with them and pretended they would let them go, before lining them up and shooting them in front of their peers.

Like Muhammad Zaid, many struck a defiant note.

"I am not scared. No force can stop me from going to attend my school. I will go and will tell the attackers, 'We are not afraid of you'," 16-year-old Zahid Ayub, who sustained minor wounds, said.

A teacher said rows of empty seats, especially in the 9th and 10th grade classes, had made the first day back at school a surreal experience.

"Students were greeting each other and saying 'You're alive?' They were taking their parents to different spots and explaining to them where they were during the time of the attack and how it happened," he said, on condition of anonymity.

"Photographs of the martyred are pasted on a noticeboard in the school. Students and teachers were placing flowers in front of it and weeping," he added.

Parents across Pakistan spoke of their fears in what was widely seen as a key moment for the country.

"Driving to school in the light of a quietly subdued rising sun. There's a kind of stillness in the air. It sounds like a million mothers saying a silent prayer as they drop their babies to school. Stay safe. Stay safe," wrote Saima Jamil Ashraf, a parent in Karachi, on Instagram.

Pakistan has strengthened its offensive against the Taliban since the Peshawar attack, ending its six-year-old moratorium on the death penalty in terror cases.

It plans to set up nine military courts to hear terrorism-related cases, prompting concern from rights groups who believe the army will use the crisis to wrest more powers from civilian authorities.

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