Park was heavily criticized as a ruthless military dictator, who in 1972 extended his rule by creating a new constitution, which gave the president sweeping (almost dictatorial) powers and permitted him to run for an unlimited number of six-year terms. The Korean economy developed significantly during Park's tenure. The government developed the nationwide expressway system, the Seoul subway system, and laid the foundation for economic development during his 17-year tenure, which ended with his assassination in 1979.