The first major reason is quantity vs. quality. Al Qaeda was forced to rely on loosely organized operatives and training provided by someone in the region. There were no 'training camps' or locations potential operatives could go to receive a 'formal training'. ISIS is different. They have developed a land hold and created camps. They are not looking for a high number of attacks; instead ISIS is looking for well planned, well executed attacks. The next major way threat is an asymmetric advantage. This is when a "weaker party" uses "violence as a political tactic against a more powerful adversary". When ISIS carries out an attack, from Nice, France to Orlando, Florida fear is instilled in many American's hearts. They are not posing a threat like a state would. Instead they are threatening the day to day lives of citizens. These attacks have inspired many across the region the join the movement, which is the third major threat to American security. The "strong horse theory" is when people support or join the strong horse, and not the weak horse. ISIS, a descendent of Al Qaeda in Iraq, is a strong horse in the region now. They have developed a peace of land with the characteristics of a state, and are representing radical ideals. This appeal will draw more and more people in, and is how the threat will continue to grow. The final threat is a result of growth, and is what happens moving forward. People have begun to fear the ideology, not so much the group of the people involved but the set of beliefs themselves. This has effectively changed the way people thinks and posses a massive risk.
I firmly believe that ISIS is a threat to America because of the reasons above. They need not kill thousands like Al Qaeda to send a message. They have begun to change the way we live our lives, they are altering our beliefs and how we view certain areas of the world and the cultures within. This change is not healthy. These fears are also relevant in our election cycle. Looking at the two candidates, one is labeled for their lack of response and the other is critiqued for using these fears to their advantage. Americans fear being attacked, we fear another shooting in a night club or being forced to stoop to the level of thieves and murderers in order to solve the issue. We fear Muslim immigrants entering the country, and we fear the government watching our every technological move. While these fears are generalized and do not apply to hundreds of millions of Americans, they exist. The existence of these fears is threat enough against the United States.