The United States has imposed sanctions on Sudan’s army chief, Abdel Fattah al-Burhan, accusing him of choosing war over negotiations to bring an end to the conflict that has killed tens of thousands of people and driven millions from their homes. The US treasury department said in a statement that under Burhan’s leadership, the army’s war tactics have included indiscriminate bombing of civilian infrastructure, attacks on schools, markets and hospitals, and extrajudicial executions. Washington announced the measures a week after imposing sanctions on Burhan’s rival in the two-year-old civil war, Mohamed Hamdan Dagalo, commander of the paramilitary Rapid Support Forces.