Air strikes and shelling rocked Khartoum on Thursday as the army attacked paramilitary positions across the Sudanese capital, witnesses and a military source told AFP. The clashes began at dawn, several residents reported, in what appeared to be the army’s first major offensive in months to regain parts of the capital controlled by the rival paramilitary Rapid Support Forces. It comes the same day Sudan’s de facto leader, army chief Abdel Fattah al-Burhan, addressed the UN General Assembly in New York. On the eve of his address, UN chief Antonio Guterres voiced concern to Burhan “about the esc…