Lumumba asked the United Nations to intervene and use military force to stop Tshombe's forces in Katanga. The first UN troops arrived on 15 July but there was instant disagreement between Lumumba and the UN over the new force's mandate. Because the Congolese army had been in disarray since the mutiny, Lumumba wanted to use the UN troops to subdue Katanga by force. Lumumba wrote to UN Secretary General Dag Hammarskjöld, that from the text of United Nations Security Council Resolution 143 "it is clear that, contrary to your personal interpretation, the UN force may be used to subdue the rebel government of Katanga." Secretary General Hammarskjöld refused. To Hammarskjöld, the secession of Katanga was an internal Congolese matter and the UN was forbidden to intervene by Article 2 of the United Nations Charter. Disagreements over what the UN force could and could not do continued throughout its deployment.