well it can be prevented by not having open shopping marts and if the shopping places are open they could put poles that prevent cars from driving into the mart
Although I feel like attacks are still a problem in the US and can occur at any time, our security is already fairly strict. Personally, I don't think anything needs to be improved.
We were taking about a similar topic today in APUSH. Unfortunately, Americans will continue giving up their rights in the face of fear and terrorism. Gulf of Tonkin Resolution 1964, Patriot Act 2001, etc. I think what we need to do is regulate our government and what they do NOW instead of waiting around for a tragedy to happen, which will inevitably lead us to give up many of our rights under the constitution.