 United Nations Security Council Resolution 161 of 21 February 1961 , called for the withdrawal of Belgian officers from command positions in the ANC , and the training of new Congolese officers with UN help . The various efforts made by ONUC to retrain the ANC from August 1960 to their effective end in June 1963 are described in Arthur House 's book The UN in the Congo : The Civilian Operations , pages 145 @-@ 155 . By March 1963 however , after the visit of Colonel Michael Greene of the United States Army , and the resulting ' Greene Plan , ' the pattern of bilaterally agreed military assistance to various Congolese military components , instead of a single unified effort , was already taking shape . 
