Even though Canada wasn't in the Congo in a combat capacity their involvement came under scrutiny from the USSR. The Soviets began to attack Canadian involvement directly, "they objected to the use of Canadian peacekeepers because Canada was one of Belgium's NATO allies." The Soviets even went so far as to demand "the withdrawal of armed groups from Canada". According to Scarnecchia, the Soviets "accused the RCAF of supplying weapons and armoured steel to Tshombe's forces in secessionist Katanga, they believed that this RCAF support was in line with Western Interests." Although these allegations were never proven, in response, the Secretary-General of the UN transferred the RCAF contingent from performing airlift duties in support of the UN mission to a Pisa-Leopoldville airlift of food and aid. This transfer served to somewhat satisfy the Russians and any further scrutiny was mild in comparison. Instead of arguing against UN involvement in the Congo, the Soviets began to provide aid to Prime Minister Lumumba in Leopoldville. Along with the assassination of Lumumba and the death of Secretary-General Hammarskjold, this then led to the use of force by UN troops in the Congo being allowed by the UN. In 1961, UN troops under aggressive commanders pushed into Katanga, and began routing Tshombe's armed forces. As "clashes between Tshombe and UN forces grew more frequent, the UN moved even more aggressively, and eventually took control of key parts of the province."