During the Japanese occupation of the Dutch East Indies, at the age of 18, he joined the Japanese-backed Defenders of the Homeland militia organization.

[1] During the Indonesia–Malaysia confrontation, due to his prior experience in Kuala Lumpur, Rustam assisted a secret effort by the Indonesian Army to maintain some relations with the Malaysian government, without the knowledge of the foreign ministry.

[4] Early in Suharto's presidency, Rustam first became the Director for Asia Pacific Affairs in the foreign ministry, before becoming ambassador to Yugoslavia in 1971 and to Malaysia in 1972.

[5] On 28 December 1974, at that time holding the rank of major general, Rustam was appointed as the acting Governor of Central Java.

[8] In the middle of his second term, Rustam was appointed as Minister of Home Affairs in the Fourth Development Cabinet, and was sworn in on 19 March 1983.

[9] In contrast to his predecessor Amir Machmud, who had significantly centralized the governance of the country, Rustam adopted a more decentralized view.

According to contemporary East Nusa Tenggara governor Ben Mboi, Rustam made studies regarding a federal government system.