Dũng planned and commanded the 1975 Spring Offensive, the final PAVN offensive that defeated South Vietnamese defenses and captured Saigon in 1975. He also directed Vietnam's invasion of Khmer Rouge Cambodia and the resulting border conflict with the People's Republic of China in 1979. He was appointed defence minister in 1980. He retired in December 1986 at the 6th National Congress of the Communist Party of Vietnam.