By Ahmed Rasheed BAGHDAD (Reuters) – More than 5 million children in Iraq need urgent assistance, the United Nations said on Thursday, calling the war against Islamic State “one of the most brutal” in modern history. “Throughout Iraq, children continue to witness sheer horror and unimaginable violence,” the United Nations Children’s Fund (UNICEF) said in a statement. “They have been killed, injured, abducted and forced to shoot and kill in one of the most brutal wars in recent history.” In Mosul, children are being targeted and killed by Islamic State militants as a way to punish families and deter them from fleeing, it said. International organizations estimate that more than 100,000 civilians, half of them children, are trapped in extremely dangerous conditions in the Old City, the last district in Mosul still under the militants’ control. More than 1,000 children have been killed and more than 1,100 injured or maimed since 2014, when the ultra-hardline militants seized large parts of Iraq, it said. More than 4,650 children have been separated from their families. The militants have lost most of the Iraqi towns they took control of after a series of U.S.-backed offensives that began in 2015. They are also on the verge of losing all of Mosul, the northern city that was their de facto capital. (Reporting by Ahmed Rasheed; editing by Hugh Lawson)