Earlier, on 19 October 1953, Abdulaziz had also appointed Crown Prince Saud as Prime Minister for the first Saudi Cabinet. Before that, he appointed him as Supreme Commander of the Armed Forces and Internal Security Units on 25 August 1953. During this period, the Armed Forces of Saudi Arabia, including the Air Force, were modernized on a large scale with American assistance. The Saudi Arabian Airlines fleet was also expanded by the purchase of four new 'Sky Masters' to primarily facilitate the transport of Pilgrims from their homes to the sites of pilgrimage and back, and also within the Kingdom. On 10 June 1953, Saud with the approval of his father also laid the foundation stone for the expansion and refurbishment of the Prophet's Mosque in Medina. Earlier on, following a visit, he had recommended to Abdulaziz the need for the adoption of this step, which the latter had sanctioned.