While the South African Government had been busying itself with perceived communist threats all around its borders, it had been brewing internal threats of its own.
Apartheid had not been well received, for obvious reasons, by those who were severely disenfranchised thereby and discriminated against.
Various movements had been established in its wake representing various portions of the South African population, that were poorly catered for under the Apartheid dispensation.
One of these was the African National Congress.
In the aftermath of the Sharpville massacre in 1960 the ANC founded a military wing called uMkhonto we Sizwe (translated Spear of the Nation) or MK.
Nelson Mandela would describe the justification for the formation of the MK later in his trial for treason in such a manner:
At the beginning of June 1961, after a long and anxious assessment of the South African situation, I, and some colleagues, came to the conclusion that as violence in this country was inevitable, it would be unrealistic and wrong for African leaders to continue preaching peace and non-violence at a time when the government met our peaceful demands with force.
This conclusion was not easily arrived at. It was only when all else had failed, when all channels of peaceful protest had been barred to us, that the decision was made to embark on violent forms of political struggle, and to form Umkhonto we Sizwe. We did so not because we desired such a course, but solely because the government had left us with no other choice. In the Manifesto of Umkhonto published on 16 December 1961, which is exhibit AD, we said:
The time comes in the life of any nation when there remain only two choices – submit or fight. That time has now come to South Africa. We shall not submit and we have no choice but to hit back by all means in our power in defense of our people, our future, and our freedom.
Firstly, we believed that as a result of Government policy, violence by the African people had become inevitable, and that unless responsible leadership was given to canalise and control the feelings of our people, there would be outbreaks of terrorism which would produce an intensity of bitterness and hostility between the various races of this country which is not produced even by war. Secondly, we felt that without violence there would be no way open to the African people to succeed in their struggle against the principle of white supremacy. All lawful modes of expressing opposition to this principle had been closed by legislation, and we were placed in a position in which we had either to accept a permanent state of inferiority, or take over the Government. We chose to defy the law. We first broke the law in a way which avoided any recourse to violence; when this form was legislated against, and then the Government resorted to a show of force to crush opposition to its policies, only then did we decide to answer with violence.
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MK, like most of the African liberation movements, naturally received support from the Soviets an other communist countries.
With the reasonably swift capture and trial of the South African based MK leadership and detention of them on Robben Island, MK had to operate mainly from outside SA borders.
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Tanzania was once again the springboard, and with effective suppression inside South Africa MK operated alongside the Zimbabwe People's Revolutionary Army against the Rhodesian Army as an Ally.
This alliance was another reason for the South Africa military and politicians to meddle in Rhodesian and Mozambican military affairs.