In the aftermath of the attacks on Paris, France wants a "grand and single coalition" against ISIS — including the US and Russia. That may be easier said than done. Prime Minister Cameron has agreed to join in conducting airstrikes against ISIS if Parliament approves; and President Putin was in Tehran for talks with Iran's Supreme Leader, who tweeted continued support for Syrian President al-Assad. But President Obama, despite facing increased calls for greater involvement, says he will only be willing if Russia abandons Syria's Assad regime. Meantime, intelligence agencies say the real threat to America is not from overseas, but from home-grown sympathizers -- especially as anti-Islamic rhetoric increases. Will US politics and diplomacy matter if Muslim countries don't lead the charge against ISIS on their own?