The Air Force has filed criminal charges against an airman in connection with an April explosion that injured US troops at a base in eastern Syria. Tech. Sgt. David D. Dezwaan Jr. is facing several charges including dereliction of duty, destroying military property, reckless endangerment and aggravated assault in the blast that injured four service members. He has been held in confinement by the Air Force since June. The US military initially reported that the injuries were caused by artillery or another form of indirect fire. But the Pentagon later said the April 7 attack was carried out by t…