Exclusive-US ties Sudanese army leader's UN visa to ceasefire plan, sources say

By Daphne Psaledakis, Nafisa Eltahir, Antoni Slodkowski and Khalid Abdelaziz Sept 22 (Reuters) - The United States is withholding a visa for Sudanese army chief Abdel Fattah al-Burhan ahead of his scheduled UN appearance in a move that Sudanese and other sources say is linked to a US-backed ceasefire proposal that Khartoum has resisted. The dispute threatens to deepen tensions between Washington and Sudan's army at a critical moment in the civil war, which the United Nations calls the world's largest humanitarian crisis.