WI US Violently Oppresses Civil Right Movement 1960's

[mtg999]

What if the US Govt (and I mean the Federal Govt either actively supportin g the oppression or not intervening at all) decided to violently oppress the Civil Rights Movement in the 1960's?

For instance jailing Martin Luther King Jr and banning the NAACP? I'm thinking here of Sth African style oppression.

Perhaps attempts made to amend the equal protection clause in order to allow open discrimination against African-Americans.

How long would such oppression be able to go on? I'm thinking here of how S African and Rhodesia were able to hang on for such a long time despite having small minorities (especially in Rhod's case) of white people.

What would be the international reaction?