How about the FBI directly: https://archives.fbi.gov/archives/news/testimony/the-terrorist-threat-confronting-the-united-states
You are characterizing "antigovernment"
Also, this gem:
In other words - no, it's not accurate to say that the left is more violent than the right.
Domestic right-wing terrorist groups often adhere to the principles of racial supremacy and embrace antigovernment, antiregulatory beliefs.
You are characterizing "antigovernment"
Also, this gem:
During the past decade we have witnessed dramatic changes in the nature of the terrorist threat. In the 1990s, right-wing extremism overtook left-wing terrorism as the most dangerous domestic terrorist threat to the country.
In other words - no, it's not accurate to say that the left is more violent than the right.