The content originally appeared on: CNN (CNN)Military bases in Iraq and Syria that hold American troops were attacked Wednesday, though no US forces were killed in the strikes, according to Iraqi officials and the US-led coalition. There have been multiple attacks this week coinciding with Monday's second anniversary of the US assassination of a key Iranian general. 'It's difficult to know with great specificity and certainty … what accounts for the frequency of these attacks,' Pentagon press secretary John Kirby […]