Yes, I and, I assumed the OP was talking about America since the statement that there aren't any leftist extremist groups is obviously untrue if you look at it

Yes, I and, I assumed the OP was talking about America since the statement that there aren't any leftist extremist groups is obviously untrue if you look at it from a world wide perceptive. That section on Wikipedia absolutely lists the left wing extremism that was common in America from the 1960's to the 1980's. I didn't look into the source of the stat listed there. But the point still stands, left wing extremism has existed in the US in the past even if it isn't the predominate problem present day.