Experts say people who suffer post-traumatic stress disorder are unlikely to act violently while experiencing a flashback.

CNN: Insights on why people 'snap' and kill

The men were "constantly moving through the crowd expressing displeasure at the crowd's unwillingness to act violently, " it says.

CNN: 5 arrested in alleged plot to blow up Cleveland-area bridge

But you don't act violently.

CNN: SHARE THIS

"For the 35 years since I founded the Sea Shepherd Conservation Society, I have strived to act non-violently and within the boundaries of the law, " Watson said.

CNN: STORY HIGHLIGHTS

After all, Earnest says, both those who perpetrate terrorist attacks and those who work to prevent them work behind the scenes, sometimes with minimal support and resources, to gather intelligence and act -- sometimes violently, but most always covertly.

CNN: Terrorism nothing new to America

In and of itself only a preparation for war, mobilization was nevertheless considered an act of war, as failure to respond quickly and if necessary, violently would result in an overwhelming advantage to the enemy.

CENTERFORSECURITYPOLICY: About that NIE��

In and of itself only a preparation for war, mobilization was nevertheless considered an act of war, as failure to respond quickly -- and if necessary, violently -- would result in an overwhelming advantage to the enemy.

CENTERFORSECURITYPOLICY: About that NIE...