A series of clashes in the last year between American and Syrian troops, including a prolonged firefight this summer that killed several Syrians, has raised the prospect that cross-border military operations may become a dangerous new front in the Iraq war, according to current and former military and government officials. The firefight, between Army Rangers and Syrian troops along the border with Iraq, was the most serious of the conflicts with President Bashar al-Assad’s forces, according to American and Syrian officials. Full Story