Turkana boys play with rifles in a village inside the Turkana region of the Ilemi Triangle, northwest Kenya, Dec. 21, 2014. The Ilemi Triangle is a disputed region in East Africa, claimed by South Sudan and Kenya, bordering also Ethiopia. REUTERS/Goran Tomasevic

Rebel militias in South Sudan have released 145 child soldiers, according to a new report from the BBC Wednesday. But that figure of newly freed children pales in comparison to the number of those who remain fighting for various groups in opposition of the government there and across the continent.

The child soldiers in South Sudan and their counterparts in the Islamic State group and elsewhere around the world have been tasked with carrying out deadly acts of war, various human rights groups say. There are about 16,000 more child soldiers in South Sudan alone, according to UNICEF.

The freed children who were fighting in South Sudan were either a part of the Cobra Faction — made up of ethnic Murle people who defected from the country's government over an inability to implement a 2014 peace agreement — or the SPLA in Opposition — the Sudan People's Liberation Movement-in-Opposition, another anti-government group. The two groups have worked together against South Sudan President Salva Kiir Mayardit, who is accused of ordering massacres of ethnic groups that violate the 2014 agreement.

Child soldiers have been recruited heavily in the East African nation since civil war broke out there in 2013, the Associated Press reported. Using child soldiers in the South Sudan has "clearly gotten worse," said Jo Becker, advocacy director of Human Rights Watch's children's rights division. "South Sudan really stands out in terms of the severity of the problem."

There have been "observations of children with armed groups, of children wearing military uniforms and carrying weapons, and of children undergoing military training," UNICIEF has said.

The international child advocacy group estimated there were about 250,000 child soldiers across the globe. Nearly half of that number is comprised child soldiers in Africa, according to Human Rights Watch. Other countries with militias using child soldiers include but are not limited to Afghanistan, India, Iraq, Philippines and Thailand.

The global terror group known as ISIS has reportedly employed similar practices to fortify its own militant ranks. From suicide bombings to executions, ISIS has also been accused of using children to carry out some of its deadliest and most grisly deeds.

In one instance, a British man said he recognized his young son killing someone in an ISIS video. Another ISIS video featured a group of young boys identified as the group's latest batch of soldiers and suicide bombers, according to Vocativ. One of the recruits explained part of his purpose for being in the group: to "become a martyr to terrorize the enemies and kill them."