Aslan joined the Syrian Army in 1956. He was trained at the Military Academy of Homs, and continued his training in the Soviet Union. He was appointed commander of the Syrian 8th Infantry Brigade in October 1966. His breakthrough came in November 1970 when he supported the military coup that brought Hafez Assad to power in Syria, and he was designated leader of the 1st and 5th Infantry Divisions of the Syrian Army. In 1972, he was appointed chief of the "operations" bureau of the Syrian Army General Staff. He commanded 5th mechanized infantry in 1973. His troops were successful in the opening stages of the 1973 Yom Kippur War, as they broke through the Israeli defensive line and drove Israeli forces out of southern and central Golan Heights. He became in charge of the Syrian Army contingent involved in Lebanon from 1976 to 1979, supervising the "hundred days war" against the Christian militia of Bachir Gemayel. At the beginning of the 1980s Aslan was deputy chief of staff and head of operations. He was appointed commander of the 2nd Corps, and promoted to lieutenant general in July 1984. In 1989, he was named assistant chief of staff of the Syrian Army, becoming the true "operational brain" of the Syrian Army. He was promoted to chief of staff on 5 July 1998, replacing Hikmat al-Shihabi who had been office in 1973 after his forced retirement. Aslan was a proponent of mandatory conscription for Syrian men, and was the main negotiator for arms deals with suppliers around the world, including Russia, China, Armenia, North Korea and Iran, as well as military treaties with Japan and several Eastern European countries. After the death of Hafez Assad in 2000, a 9-member committee was formed to oversee the transition period, and Aslan was among its members. In addition, he became a member of the Baath Party's central committee in the Summer of 2000. Aslan was one of the senior officials, who contributed to secure the rule of Bashar Assad. However, he was relieved from his post as chief of staff by Bashar Assad in January 2002, as part of the younger president's program of reform and after reported clashes with Assef Shawqat regarding personnel changes. Aslan was replaced by his then deputy, Hassan Turkmani. Aslan was later appointed military advisor to the president. In June 2005, Aslan was removed from the central committee of the Baath Party, and he retired from politics.
