Yes it can and already has. We have home grown terrorist already in the United States. Should we live our lives in fear? Hell NO! All the US can do is limit assess to certain chemicals and weapons and monitor the known or suspect terrorists more closely. The purpose of terrorism is to interrupt our daily lives and cause us to fear. I refuse to live in fear!

Nancy Pelosi is scared to death of the Tea Party radicals.

Nice hit there, Speedy. You know, terrorism can be categorized and it should be. It should also NOT BE LIMITED TO ONLY THOSE OF OTHER COUNTRIES AND RELIGIONS, folks. Listen, we just had AN AMERICAN murder students the same way they do in the Middle East. We also had AN AMERICAN kill nine people who were at church spending time with God. Are these individuals NOT terrorists???? Oh, but the Boston Bombers WERE terrorists...right??? People that kills cops...are they NOT terrorists?? Are the cops that seek to kill only or mostly blacks NOT terrorists?? Let's have a look at the definition of the word:

ter·ror·ism
ˈterəˌrizəm/Submit
noun
the use of violence and intimidation in the pursuit of political aims.

You know, I could really, really work this thing over but I'd then be into 'essay mode'. Short answer: we experience terrorism every single day. Mass shootings and gang violence are designed to do exactly what's in the definition. Everything falls into one of two categories: POLITICAL or CULTURAL (RELIGION). Yeah, I know, "That's some REAL GOOD KOOL-AID, LUCKY!!!!" I spiked it with some top shelf Tequila.