Among many other more noble things, Martin Luther King, Jr, was a mid-20th centrury embodiment of a colonial project started in the Americas as far back as the mid-1700s. The project was an attempt to equate acts of force in the mind of the oppressed with acts of violence. Thus, when he spoke of non-violence, the subtext was, at least initially, “non-force”.
This call for the use of non-force in American public protest was championed by colonial aristocrats prior to the American Revolution when dealing with the disgruntled masses who despised the economic disparities that kept them poor while making others rich. It was only when the propensity for the forceful redistribution of wealth and privilege could be channeled violently toward the British–to oust the British for the benefit of colonial aristocrats–that the use of force was re-characterized as moral. It has since been the case that every American act of war which has enriched a few while impoverishing many has been judged by those who have profited as being moral, while every forcible attempt to bring about increased economic equity has been judged immoral.
Being the brilliant mind that he was, MLK eventually subverts this moral prestidigitation by turning his indignation toward those who do violence without force, which is when he got himself killed. What he began to equate in 1968 was that poverty (violence minus force), the militarism of the Vietnam War (violence through force) and racism (violence with or without force) were all violence, one and the same. One has to respect this commitment to moral consistency.
However, it leaves the question of the appropriate use of force unanswered. Is there a use of force that is not inherently violent?