The colonial administration implemented a variety of economic reforms to improve infrastructure: railways, ports, roads, mines, plantations and industrial areas.

On 1 July Lumumba sent a wire to the UN to request membership, stating that the Congo "accepts without reservation the obligations stipulated in the Charter of the UN and undertakes to abide by the same in absolute good faith.

"[4] UN Secretary-General Dag Hammarskjöld cabled the Foreign Ministry, pointing out the difficulty in admitting the country into the UN under its name in the face of another application for membership from the neighboring Congo, preparing for independence from French control.

[5] In September 1960 the Fourth emergency special session of the United Nations General Assembly needed to be called in the wake of a Security Council veto by the USSR.

Hammarskjöld's second term was cut short when on 18 September 1961 he died in a plane crash near Ndola, Northern Rhodesia while en route to cease-fire negotiations during the Congo Crisis.

[citation needed] Lumumba had previously appointed Joseph Mobutu chief of staff of the new Congolese army, the Armee Nationale Congolaise (ANC).

The aversion of Western powers towards communism and leftist ideology, in general, influenced their decision to finance Mobutu's quest to maintain "order" in the new state by neutralizing Kasa-Vubu and Lumumba in a coup by proxy.

[citation needed] On 17 January 1961, Katangan forces, supported by the Belgian government, which desired to retain mining rights for copper and diamonds in Katanga and South Kasai, executed Patrice Lumumba and several of his aides at a pig farm near Élisabethville.

[citation needed] On at least three occasions over the next two years, Katangan forces under the command of foreign mercenaries clashed with the ONUC, but in February 1963 Katanga was reintegrated into the national territory.