As the hot weather arrives in Gaza, teenagers head to the town of Rafah for summer camp -- not to play sports but to join war games organised by radical Palestinian group Islamic Jihad.
Youngsters wearing military fatigues and the movement's black insignia capture a fellow camper posing as an Israeli soldier and drag him away -- all part of being trained to "resist" the enemy.
Around 100 children under the age of 16 learn from members of Islamic Jihad's armed wing Al-Quds Brigades how to strip down an AK-47 assault rifle, crawl through tunnels and run across burning tyres amid the sound of explosions on their assault course.
"When I'm older I want to fight in Al-Quds Brigades and capture Israeli troops," said 12-year-old Ezz, who was this time playing the role of the unfortunate enemy soldier taken from his position atop a scorching sand dune.
Ezz is a pupil at a school in the Gaza Strip run by the UN's Palestinian refugee agency UNRWA.
Fellow camper Osama, holding a rifle, explains: "We learn to fight so that we're ready for our resistance against the Zionist enemy (Israel) who occupies our land and kills us."
The head military trainer at the camp, Abu Khaled, insists it is like any other "youth camp, (but) includes combat training."
The Al-Quds Brigades instructor, wearing a balaclava, says he sees the "soldiers of the future" in the children he is training, adding that his eldest son is taking part in the two-week camp.
"We want to instil the notion of kidnapping (Israeli) soldiers so that we never forget our prisoners," he says, referring to previous prisoner exchange deals between the Jewish state and Palestinian groups.
In one of the most significant such swaps, Gaza rulers Hamas released captured Israeli soldier Gilad Shalit in exchange for over a thousand Palestinian detainees in an October 2011 deal.
Abu Mohammed, another instructor, insists "there's no need for children to actually fight. But we train them to, so they can face danger and the fear of (aerial) bombardment."
The Hamas movement ruling Gaza, meanwhile, has opened its own summer camps to some 100,000 students, boys and girls, aged 10 to 21.
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Although not as overtly military-focused as those of Islamic Jihad, the Hamas camps also include rudimentary combat training.
"They're focused on creativity and fun as well as religious, moral and national education on the right of return of Palestinian refugees and the prisoners issue," says Mussa al-Samak, one organiser.
But Mohammed al-Shawa, a counsellor for activities being organised in the Shati refugee camp in Gaza, says the aim is "fun, education and learning basic martial arts."
A Gaza psychologist, requesting anonymity, criticised the participation of children in military exercises.
"This presents a danger to their lives and contravenes international laws for the protection of children," he said.
"We always warn against the use of children in conflicts, whether they're just training or actually being used as part of the resistance against the Israeli occupation," he stressed.
"It's as if certain groups want to say, 'in training children for combat, we're still resisting'," he said, referring to reports that extremist Gaza-based groups were being prevented from firing rockets into Israel by Hamas units deployed along the border.
Rocket fire from the besieged territory has dipped significantly since a November ceasefire that ended an eight-day conflict between Hamas and Israel.
Every summer since Hamas took control of the Gaza Strip in 2007, the territory sees competition between the Islamist movement's summer camps and those organised by UNRWA.
But in 2012, a cash-strapped UNRWA was forced to cancel its "summer games" which would attract up to 250,000 children.
The UN agency has from June 15 to July 4 this year reopened its activities, which include football and kite-flying, to a more modest 150,000 children, thanks to a donation from Finland, it said in a statement.
"UNRWA's Summer Fun Weeks are a much needed break from the harsh reality of the environment and are therapeutic for children living under a crippling blockade and scarred by poverty and violence," it said.