compare and contrast

Why were extremist elements of the New Left in the United States able to construct a fairly viable underground movement during the 1960 – 80s?  Why did this underground not involve itself in the same scale of terrorist violence that emerged at the same time among leftists in Germany and Italy?

Why has the extremist right in the United States never formed a viable terrorist underground despite pronouncements from some adherents that they are prepared to do so?

1 page-double spaced, intext citations, times new roman