Operation Big Switch, August 5–December 23, 1953, was the final exchange of prisoners of war by both sides, and, like Little Switch, was marked by controversy over voluntary repatriation and, later, by allegations of brainwashing and torture of U.N. POWs by the Communists. The issue of forced repatriation of POWs proved the major stumbling block to successful conclusion of the truce talks. Communist insistence on the return of all captured nationals held by the U.N.C. was strenuously opposed by the U.S. and South Korean governments, although a number of the other governments who had committed forces to the U.N. command in Korea argued that the principle of voluntary repatriation should not be permitted to obstruct an early conclusion of hostilities. Eventually it was agreed that a U.N. Neutral Nations Repatriation Commission (N.N.R.C.), chaired by India, would take responsibility for prisoners who had indicated a desire to remain with their captors. During a 90-day period in which the N.N.R.C. held custody of the “non-repatriates,” a series of “explanations” was provided during which the non-returnees were advised strongly to return to their home nations, generally without success.