Key moments from the U.S.-led campaign in Iraq and Syria

US.-led forces have been carrying out airstrikes against Islamic State militants in Iraq and Syria since 2014, but have tried to avoid getting drawn into Syriaís ruinous civil war. On Thursday, President Trump authorized the deployment of cruise missiles against a Syrian air base in retaliation for an apparent poison-gas attack that U.S. officials say was carried out by President Bashar Assadís military.