Property lines, buildings vs. trees?

I’m in Idaho, and have a garage (built in 1951), which was built right on one of my property lines. Some new people from out of state bought the adjoining property, four years ago. They are invasive people, used to getting their way.

They planted several emerald green Arborvitae (similar to Cedar), right next to the shared property line. One is within three feet of the side of my garage. The Arborvitae, are already 4+ feet wide, and 17 feet tall. The branches are only 6 inches from my garage’s eves.

From what I’ve read they will get much bigger, and are considered a fire hazard, due to their ‘Cedar-like’ volatile oils.

Does anyone have any advice? Is there anything I can legally do about this situation?