its first director. In December 1962, a referendum was held on returning to a presidential system of rule, which was allegedly passed with a 78% majority. Park and the other military leaders pledged not to run for office in the next elections. However, Park became presidential candidate of the new Democratic Republican Party (DRP), which consisted of mainly KCIA officials, ran for president and won the election of 1963 by a narrow margin. Third Republic (1963–1972) Park's administration started the Third Republic by announcing the Five-Year Economic Development Plan, an export-oriented industrialization policy. Top priority was placed on the growth of a self-reliant economy and modernization; "Development First, Unification Later" became the slogan of the times and the economy grew rapidly with vast improvement in industrial structure, especially in the basic and heavy chemical industries. Capital was needed for such development, so the Park regime used the influx of foreign aid from Japan and the United States to provide loans to export businesses, with preferential treatment in obtaining low-interest bank loans and tax benefits. Cooperating with the government, these businesses would later become the chaebol. Relations with Japan were normalized by the Korea-Japan treaty ratified in June 1965. This treaty brought Japanese funds in the form of loans and compensation for the damages suffered during the colonial era without an official apology from the Japanese government, sparking much protest across the nation. The government also kept close ties with the United States, and continued to receive large amounts of aid. A status of forces agreement was concluded in 1966, clarifying the legal situation of the US forces stationed there. Soon thereafter, Korea joined the Vietnam War, eventually sending a total of 300,000 soldiers from 1964 to 1973 to fight alongside US troops and South Vietnamese Armed Forces. Economic and technological growth during this period improved the standard of living, which expanded opportunities for education. Workers with higher education were absorbed by the rapidly growing industrial and commercial sectors, and urban population surged. Construction of the Gyeongbu Expressway was completed and linked Seoul to the nation's southeastern region and the port cities of Incheon and Busan. Despite the immense economic growth, however, the standard of living for city laborers and farmers was still low. Laborers were working with low wages to increase the price competitiveness for the export-oriented economy plan, and farmers were in near poverty as the government controlled prices.