spilling over to lebanon as taken several leaders from the former prime minister hariri until now. there has been a protracted effort to knock out anti-shia islamists in lebanon. so this pro-western figure was part of a government that was pushing back on those shia islamist that is have taken over syria. harris: the civil war is playing out next door in syria yet our reporter conor powell this hour told us lebanon is a dangerous mess. why? >> it has proximity and iran has a decades-long relationship with hezbollah. terrorist vanguard, hezbollah has conducted violent attacks in lebanon and the broader region for some time. this arc of instability comes from tehran all the way to the mediterranean that is guiding these events right now. harris: all right. sit tight. we'll come right back to you. leland? leland: important stories ahead. including every year hundred of thousands of americans have knee surgery. now a new study warns that surgery may not actually be