U.S. President Donald Trump has ordered an attack with cruise missiles on a Syrian airfield on Thursday. This comes in the wake of attacks involving the alleged the use of Sarin gas in rebel held areas, which according to the Trump administration was carried out by Syrian government forces. Up to 60 cruise missiles were fired from two U.S. Navy destroyers in the Mediterranean in apparent retaliation.
While this was the first time America directly attacked Syrian government forces, the air war over Syria has been ongoing. So far, the so-called Operation Inherent Resolve (OIR) has mostly targeted positions controlled by the Islamic State in Iraq and Syria. Most strikes by far are carried out by the U.S. Air Force.
All Syrian chemical weapons should have been destroyed. From October 2013, the Organisation for the Prohibition of Chemical Weapons (OPCW) oversaw the destruction of Syria's stockpile. However, there have been doubts this really happened. Syria signed the Chemical Weapons Convention, which bans the use of such weapons, in mid-september 2014.