I don't agree, terrorists are inherently cowards, yes they are willing to die for a cause, but they are low life cowards with no honour and no bravery.
They attack soft easy weak targets, they kill women and children generally out having a good time and with no protection or way of defending themselves.
They have been doing these attacks in the UK where police and public are generally unarmed, the US have heavily armed police that do not take any prisoners and have no hesitation using deadly force, in many states they also have armed citizens that would only be to happy to put a cap in the ass of a terrorist, I am sure there are many 'crazy's' in the US training for and awaiting this opportunity.
Even in Australia Police carry .40 cal Semi Automatic Glock handguns and spare magazines of ammunition, most have by now undergone an intensive take no prisoners anti terrorism training course and are quite capable of dealing with an armed thread.