The United States is inching closer to involvement in the Syrian civil war after U.S. forces shot down a Syrian fighter jet on Sunday.  The incident is the fourth time in as many weeks that the United States has shot at pro-Syrian-government forces, and it carries the potential for further escalation — particularly with Russia threatening to target U.S. aircraft that

fly into parts of Syria. A statement from the U.S. military said it shot down the Syrian SU-22 in self-defense and after contacting Russian counterparts through the established deconfliction zone. The Syrian aircraft was bombing U.S.-backed forces fighting the Islamic State in Iraq and Syria (ISIS) south of Tabqa. It was the first time the United States has shot down a Syrian plane, and the first time a U.S. military jet has shot down any manned aircraft since 1999. READ MORE