Twenty-one civilians were killed in US-led coalition air strikes against Islamic State targets in Iraq and Syria in recent months. <br/><br/>Officials acknowledged this today. The deaths bring to at least 220 the number of civilians unintentionally killed since operations to defeat IS began in late summer 2014. Critics, however, say the real number is a lot higher.''<br/>'<br/>A statement from the coalition said investigators had probed a series of reports alleging civilian deaths from air strikes.'<br/>'<br/>Airwars, a London-based collective of journalists and researchers, uses local sources, photographs and media accounts to keep a detailed list of every known coalition air strike.<br/><br/>They have praised Pentagon efforts at accountability compared to other players in Syria such as Russia and the regime of President Bashar al-Assad. But the group says the number of likely civilian deaths from coalition strikes is 2,463 at a minimum.