Is graffiti art considered a "terroristic threat" in the US now?

Excuse me? First of all, spray painting any public property without the owner's consent is both reprehensible and illegal, especially if it is federal property. Secondly, this particular crime isn't considered a "terroristic threat" (I have not heard of such a term relating to graffiti). This is a crime which involves defacing public property. If it doesn't belong to you, and it is not granted permission by the property owner, then it is illegal. It has nothing to do with terrorism unless the words or deeds incite terrorism. Graffiti is indeed an artform, and the unfortunate part is, it is an artform that would be decent if it were allowed and if it were respected. The problem is, graffiti artists (not all of them but many of them) do not use their talent to upbuild the environment around them. It is simply a tool used in rebellion against an establishment or it is reckless behavior. I actually like this kind of art only because it is unique, but it has its place, and it does not belong on a federal or private building, especially without consent.

Terrorism: "the unofficial or unauthorized use of violence and intimidation in the pursuit of political aims". (Oxford Dictionaries Online) Graffiti isn't characterized by the use of violence or intimidation. Neither is graffiti used to achieve political aims. So, the answer is no.

I wouldn't worry about it too much. Christian gun owners are their real fear.

I find some graffiti quite talented....think Keith Herring ........

I have seen pictures of some very good grafitti in NYC. Where I live, the grafitti consists of obscenities. Usually in a park, or downtown. It's like porn...it has no value. .

Not really - depending on the message painted. That said - littering, being a public nuisance, vandalism, etc... are still crimes. Extremely minor but still not right. The idea of Government property being 'owned' by all is sometimes misleading.