In 2003, Iraq suffered from an unprovoked attack and illigeal invasion by the USA and a concocted coalition on the basis of two false premises. One was that Iraq was connected to the 9/11 Twin Towers attack when it was well know that the support and funding came from Saudi Arabian sources. The other was that Saddam Hussein had built up an arsenal of weapons of mass destruction which, in reality, did not exist.
This invasion was not welcomed by the people of Iraq. This invasion broke down established protection of minority religious groups including Jews and Christians and attracted terrorist groups such as al Qaeda closely linked to Saudi Arabia and followers of the austere intolerant version of Islam which is promoted worldwide by Saudi Arabia.
The incompeence of US military led to the entry of other fanatical groups who wished to sequester Iraqi territory for form new Caliphate. In those areas captured by this group (ISIL) non-Moslems, Shia Moselems and lange numbers of Christians and other minority religious groups were murdered, the women sold into sex slavery.
The most successful fighting against these fanatical groups was carried out by the Kurds and later the Iraqi army with US help. However, the US airforce and coalition forces ended up killing a very large number of civilians opting for drones and remote fighting techniques rather than direct confrontation.