Because of Buthelezi's former position in the African National Congress, the two organisations were initially very close and each supported the other in the anti-apartheid struggle. However, by the early 1980s the Inkatha had come to be regarded as a thorn in the side of the ANC, which wielded much more political force through the United Democratic Front (UDF), than Inkatha and the Pan Africanist Congress. Although the Inkatha leadership initially favoured non-violence, there is clear evidence that during the time that negotiations were taking place in the early 1990s, Inkatha and ANC members were at war with each other, and "Self-Protection Units (SPUs)" and "Self-Defence Units (SDUs)" were formed, respectively, as their protection forces.