As US forces continue to withdraw from Iraq, many fear a return to sectarian violence once they've gone. Iraqi Christians are particularly fearful of the removal of the main barrier between them and their persecutors. Their churches are burnt-out husks and heaps of rubble. Their businesses are targeted by extremists. Their leaders are kidnapped and assassinated. The Christian minority in Iraq, once a community left in peace to prosper, continues to be under threat from a campaign of persecution which has forced as many as 500,000 Christians to flee the country. During the reign of Saddam Hussein, the estimated 1.4 million Christians - many of them Chaldean-Assyrians and Armenians, with small numbers of Roman Catholics - were generally left alone if they didn't oppose the government and they lived in relative peace with the country's Sunnis and Shiites. Some, such as Tariq Aziz, Saddam's foreign minister and deputy prime minister, rose to the highest levels of power. Things changed after the 2003 US-led invasion of Iraq toppled Saddam's regime. Christians became a target of violence when Islamist groups and ordinary Muslims angered by the military action began seeing them as the enemy, associating with them with the "crusaders" - the invading armies of the United States and Britain. Tensions over their religious ties with the West and their differing beliefs to the strict Islamic majority, which had been simmering for years, spilled over as the occupying forces dug in. "Iraqi Christians became caught up in the overlapping violence and multiple conflicts unleashed after 2003," Dr. Kristian Ulrichsen, an Iraq expert at the London School of Economics and Political Science, told Deutsche Welle. "They became exposed to the similar patterns of kidnappings, extortion, beheadings, rape and forced taxation that affected all other communities as the erosion of central government control left a security vacuum that was exploited by organised and opportunistic criminality and anti-occupation resistance groups." "In addition to this, Christians specifically were targeted by Church bombings and assassination attempts owing to a perceived association with the aims and intentions of the occupying forces." Association with occupying powers makes Christians targets In 2004, insurgents launched a coordinated bombing campaign targeted churches in Baghdad. In 2007, after Pope Benedict XVI made comments perceived to be anti-Islam, nationwide attacks on churches hit an all-time high and a priest in the northern city of Mosul was kidnapped and later found beheaded. In January 2009, 40 Iraqi Christians were killed and approximately 12,000 fled their homes. An Iraqi man is helped from rubble outside a church after a car bomb attack in BaghdadBildunterschrift: Gro