Yes, an attack from ISIS or another terrorist group is a definite possibility and something I'm sure is being addressed by security advisers. Any time there is an event where large numbers of people are gathered, where there is worldwide media coverage, where there is a positive goal, there is a likelihood of an attack. On the other hand, we should not necessarily cancel all events in fear. We must move on with caution, but never fear.
In the wake of the brutal terrorists attacks by ISIS over the past several years, there is reason to be concerned that the 2016 Olympics in Rio might be targeted as well by the group. ISIS has been successful at hitting soft targets, and the Olympic games would make an ideal venue for them to attack. The World needs to do more to provide security for the games in Rio.
No, I do not believe that an ISIS attack will happen at the Rio Olympics in 2016. We constantly live in fear of an attack and unfortunately we can't prevent it. I'm not saying there will or won't be an attack, but it's pointless living in fear. The authorities are trying to prevent any attack, and they do in fact prevent a lot, but the terrorists will always find a way to get in, we can't prevent this from happening, the Orlando Shooting proves this fact.
No, I do not fear that an ISIS attack will happen at the Rio Olympics because i'm confident that the Brazilian government is taking necessary steps to ensure that an attack won't happen. I think it more likely that problems such as the Zika virus and Brazil's political unrest disrupt the Rio Olympics instead of terrorist attack.