Mahathir was a strong proponent of strengthened affirmative action for the Malays, and reportedly demanded (together with Syed Nasir Ismail and Syed Jaafar Albar) a one-party Malay-only government led by UMNO in the wake of the May 13 racial riots in Kuala Lumpur, the Malaysian capital. He would later author "The Malay Dilemma", which contended that the Malays as the "definitive people" of Malaysia had a birthright guaranteeing them special privileges such as those outlined by Article 153 of the Constitution of Malaysia. Musa, who was closely associated with Mahathir, thus became also associated with Mahathir's "ultra" approach to politics. Both would later be expelled from UMNO by then Prime Minister and UMNO President Tunku Abdul Rahman after Mahathir's reaction to the May 13 riots. Then Home Minister Ismail Abdul Rahman would issue an explanation of the decision where he stated: "These ultras believe in the wild and fantastic theory of absolute dominion by one race over the other communities, regardless of the Constitution." Musa and Mahathir would later be rehabilitated by the Tunku's successor, Tun Abdul Razak.