BEIRUT (Reuters) - More than 200 fighters have joined Islamic State in Syria's **rthern Aleppo province since U.S. President Barack Obama said the United States would strike the militant group in Syria, a monitoring group said on Friday. U.S.-led forces launched air strikes on Syria on Tuesday, concentrating raids on the **rth and east to loosen Islamic State's grip on Syria's oil and its presence along the border with Iraq. At least 162 people joined the radical al Qaeda offshoot in **rtheast and eastern Aleppo in the week after Obama's speech on Sept. ...