cell phones and internet traffic for chatter about attacks. if an attack is proven, and if president obama were to order military action, cnn has learned turkish and u.s. aircraft in southern europe are close enough to launch air strikes. the u.s. navy is also maintaining a classified submarine presence in the mediterranean, along with surface warships that could fire missiles to destroy chemical fights. >> we are looking at a wide range of operations, and we are prepared, if called upon, to be engaged. >> now, intelligence officials say, because there are no u.s. operatives or u.s. military personnel on the ground inside syria, it may be very difficult to prove what did happen there. they may never really know. brianna? >> barbara starr at the pentagon. the obama noted israel's security can be measured in near