Chronicles of domestic terrorism in United States of America, part 1: excerpts from various sources.

Black Separatists: 
This group is termed as a hate motivated group movement and is mostly comprised of the Nation of Islam and New Black Panther Party. This group typically opposes integration and racial intermarriage, and they want separate institutions or even a separate nation for blacks. Most forms of black separatism are strongly anti-white and anti-Semitic. In early 1990s, the New Black Panther Party for Self Defense (NBPP) threatened to launch urban guerrilla warfare if the black urban poverty was not alleviated with large infusion of government funds. They have used confrontational-armed demonstrations to get media attention; disrupted Dallas school board meetings calling for separate schools; etc… despite their increasing attention, this group has not been accepted by many blacks, thus have been labeled as racist by many across the nation. However, the rise of this group can be explained in part as a retaliatory response to what they termed as oppression under white supremacist government. http://www.adl.org/learn/ext_us/Black_Panther.asp

Revolutionary Leftists:
these are left wing extremists who profess the views to reform or overthrow the established governmental order for the well being of the common man. Most prominent among these advocates were the Student for Democratic Society and Weather Underground, and the Black Panthers.
The original SDS sought to promote greater active participation of American students thru the resolution of existing problems that included: racism, poverty, unemployment, campus injustice, and free speech. Their main targets were the government establishments and the university’s paternalism. Hence, this early movement was not a form of terrorism.

As the group grew, a radical group called the Weather Men branched from the SDS to form a militant group with a very clear objective of using terror; they believed that destruction was an act of positive resistance. In 1970s, they launched revolution against the government by attacking it institutions like the June 9, 1970 New York Police station bombing and carrying out other acts of violence thru 1974.

The Black Panthers were another revolutionary leftist group. It had a humble beginning as a nonviolent; however, this approach did not bring any change to their cause of social justice and equality.  The Panthers resulted to using violence in hopes to overthrow the existing American social order reinforced by all-white police force. In May 1967, a contingent of panthers burst into California legislative session armed with guns to prove their right to bear arms; armed black students responding to threats by white students on campuses across the nation, etc...

References:
Hewitt, Christopher. Understanding Terrorism in America: From the Klan to Al Qaeda.

Vohryzek-Bolden, M. Olson-Raymer, G. and Whamond,  J. O. Domestic Terrorism and Incident Management: Issues and Tactics. Springfilled, IL: Charles C. Thomas      

Southern Poverty Law Center - Fighting Hate, Teaching Tolerance, Seeking Justice
http://www.splcenter.org/