President Obama vowed to track down and destroy terror cells all over the world last night as he finally ended his silence over a failed Christmas Day plot to blow up an American passenger jet. The White House said Mr Obama’s reticence to speak out was designed to reduce the attention focused on an extremist group based in Yemen calling itself al-Qaeda in the Arabian Peninsula. The Islamist organisation led by a former personal secretary to Osama bin Laden claimed responsibility for the botched attack in a statement yesterday. The President took a few minutes out of his holiday in...