If you look at the govt announcement it cites:
>multiple high-profile instances of breaking into defense infrastructure and British military installations, and causing millions of dollars’ worth of damage to military equipment. Palestine Action has promoted its violent, criminal, and terrorist acts on social media, encouraging the use of similar tactics internationally, including within the United States and along the U.S.-Mexican border.
and the like https://home.treasury.gov/news/press-releases/sb0616
So it's breaking in and destroying stuff which is illegal, not the far left.